Amcheck verification of GiST and GIN

From 35922b26ae10b131216746fed1890a2e255b811d Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Thu, 22 Jul 2021 10:08:47 +0300
Subject: [PATCH v11] Amcheck for GIN and GiST

Author: Grigory Kryachko, Heikki, Andrey
Discussion: https://www.postgresql.org/message-id/CAF3eApa07-BajjG8%2BRYx-Dr_cq28ZA0GsZmUQrGu5b2ayRhB5A%40mail.gmail.com
---
 contrib/amcheck/Makefile                |   8 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  24 +
 contrib/amcheck/amcheck.c               | 187 ++++++
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/amcheck.h               |  27 +
 contrib/amcheck/expected/check_gin.out  |  60 ++
 contrib/amcheck/expected/check_gist.out | 119 ++++
 contrib/amcheck/sql/check_gin.sql       |  40 ++
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gin.c            | 801 ++++++++++++++++++++++++
 contrib/amcheck/verify_gist.c           | 524 ++++++++++++++++
 contrib/amcheck/verify_nbtree.c         | 306 +++------
 doc/src/sgml/amcheck.sgml               |  38 ++
 13 files changed, 1947 insertions(+), 231 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gin.c
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..db8f8112da 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,14 +3,18 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
+	verify_gin.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+	amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gin check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..54180d356d
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,24 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+--
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..7a222719dd
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,187 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..c4c0cfd94d
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,60 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array', true);
+ERROR:  "gin_check_text_array" is not an index
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..568a67ebe2
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..45f3bb47c7
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,801 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "miscadmin.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state);
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+				// XXX: Why do we have invalid pointers here?? Got an SegFault without this check
+			if (!GinPageIsLeaf(page) && ItemPointerIsValid(&(idxtuple->t_tid)))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..7c06982ab8
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,524 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "miscadmin.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints B-Tree index */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static GistCheckState gist_init_heapallindexed(Relation rel);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static GistCheckState
+gist_init_heapallindexed(Relation rel)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+	GistCheckState result;
+
+	/*
+	* Size Bloom filter based on estimated number of tuples in index
+	*/
+	total_pages = RelationGetNumberOfBlocks(rel);
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	/* Generate a random seed to avoid repetition */
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	/* Create Bloom filter to fingerprint index */
+	result.filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	/*
+	 * Register our own snapshot 
+	 */
+	result.snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result.snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+	
+	return result;
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	if (heapallindexed)
+		check_state = gist_init_heapallindexed(rel);
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+	
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 * 
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index a8791000f8..d12c55b478 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -40,6 +40,8 @@
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -137,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -183,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -202,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -225,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -241,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -397,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -792,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -874,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1092,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1128,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1441,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1734,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1744,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1864,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1968,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2019,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2106,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2338,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2362,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2411,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2781,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2904,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3142,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,44 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From 2a0b582407d2c180e31ca278a61d0a128d64726f Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v12 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 ++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/verify_nbtree.c | 306 ++++++++------------------------
 4 files changed, 295 insertions(+), 228 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..0194ef0d7a
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index a8791000f8..d12c55b478 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -40,6 +40,8 @@
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -137,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -183,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -202,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -225,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -241,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -397,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -792,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -874,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1092,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1128,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1441,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1734,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1744,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1864,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1968,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2019,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2106,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2338,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2362,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2411,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2781,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2904,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3142,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.32.0 (Apple Git-132)

From 25f4940f334d51109e881abcfd439ab627de0685 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v12 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 520 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 7 files changed, 719 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..db65880d87
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,520 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "miscadmin.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints B-Tree index */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static GistCheckState gist_init_heapallindexed(Relation rel);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static GistCheckState
+gist_init_heapallindexed(Relation rel)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+	GistCheckState result;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = RelationGetNumberOfBlocks(rel);
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result.filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result.snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result.snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+	
+	return result;
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	if (heapallindexed)
+		check_state = gist_init_heapallindexed(rel);
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+	
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 * 
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From b928670494a831f3925705a9f7cc0a60e914fb57 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v12 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/expected/check_gin.out |  60 ++
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 801 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 6 files changed, 932 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..c914e6d0ba 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..c4c0cfd94d
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,60 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array', true);
+ERROR:  "gin_check_text_array" is not an index
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..568a67ebe2
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..45f3bb47c7
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,801 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "miscadmin.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state);
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+				// XXX: Why do we have invalid pointers here?? Got an SegFault without this check
+			if (!GinPageIsLeaf(page) && ItemPointerIsValid(&(idxtuple->t_tid)))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From b5bfc240b5cebcaec7b3ccd213710188b430d7b5 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v13 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 ++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/verify_nbtree.c | 306 ++++++++------------------------
 4 files changed, 295 insertions(+), 228 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..0194ef0d7a
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 2beeebb163..d12c55b478 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -40,6 +40,8 @@
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -137,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -183,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -202,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -225,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -241,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -397,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -792,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -874,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1092,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1128,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1441,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1734,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1744,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1864,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1968,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2019,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2106,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2338,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2362,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2411,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2781,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2904,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3142,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.32.0 (Apple Git-132)

From 9eb322531c9ec74cb6e8ef0910d54f46f2f82f08 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v13 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 520 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 7 files changed, 719 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..db65880d87
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,520 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "miscadmin.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints B-Tree index */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static GistCheckState gist_init_heapallindexed(Relation rel);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static GistCheckState
+gist_init_heapallindexed(Relation rel)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+	GistCheckState result;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = RelationGetNumberOfBlocks(rel);
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result.filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result.snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result.snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+	
+	return result;
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	if (heapallindexed)
+		check_state = gist_init_heapallindexed(rel);
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+	
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 * 
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From e45cc422aea129d35da8b521580379cf78ad430b Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v13 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 800 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 936 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..c914e6d0ba 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 0194ef0d7a..1e0c875926 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..d98d525c66
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..789259e662
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..90fe89501d
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,800 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "miscadmin.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state);
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From 5c6709a38561adf4cf2d6f72ad5fcd86fdf4bbde Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v14 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 520 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 722 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d5..a8174195817 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 00000000000..93297379efe
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f754..e67ace01c99 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..9749adfd340
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 227e68ff834..d84138f7fa6 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck = shared_module('amcheck', [
     'amcheck.c',
+    'verify_gist.c',
     'verify_heapam.c',
     'verify_nbtree.c',
   ],
@@ -13,6 +14,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -25,6 +27,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..75b9ff4b436
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..db65880d871
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,520 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "miscadmin.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints B-Tree index */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static GistCheckState gist_init_heapallindexed(Relation rel);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static GistCheckState
+gist_init_heapallindexed(Relation rel)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+	GistCheckState result;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = RelationGetNumberOfBlocks(rel);
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result.filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result.snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result.snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+	
+	return result;
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	if (heapallindexed)
+		check_state = gist_init_heapallindexed(rel);
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+	
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 * 
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936f..9397a69c6e5 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.37.3.542.gdd3f6c4cae

From 5af85c93cb961040c5e256f79db38d285c5f1fb7 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v14 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 800 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 938 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a8174195817..ecb849a605b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379efe..c914e6d0baa 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 0194ef0d7a2..1e0c875926c 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..d98d525c660
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index d84138f7fa6..0d7d651b24a 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck = shared_module('amcheck', [
     'amcheck.c',
+    'verify_gin.c',
     'verify_gist.c',
     'verify_heapam.c',
     'verify_nbtree.c',
@@ -28,6 +29,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..789259e6629
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..90fe89501d8
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,800 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "miscadmin.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state);
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e5..7ffa36b2057 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.37.3.542.gdd3f6c4cae

From 9c2919df1419216e596819e9a3e23616d431d8d0 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v14 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 308 ++++++++------------------------
 5 files changed, 297 insertions(+), 229 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50b..f10fd9d89d5 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 00000000000..0194ef0d7a2
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 00000000000..10906efd8a5
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1db3d20349e..227e68ff834 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,4 +1,5 @@
 amcheck = shared_module('amcheck', [
+    'amcheck.c',
     'verify_heapam.c',
     'verify_nbtree.c',
   ],
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 9021d156eb7..950014f19d5 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -41,6 +41,8 @@
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +140,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +184,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +208,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +236,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +255,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
-						RelationGetRelationName(indrel))));
-
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
 					allequalimage;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
+						RelationGetRelationName(indrel))));
 
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +320,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +692,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +774,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +992,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1028,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1341,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1634,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1644,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1764,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1868,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1919,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2006,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2238,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2262,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2311,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2681,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2804,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3042,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.37.3.542.gdd3f6c4cae

From 215a18b266ade415edbc014a36ecdceb20168b1b Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v15 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 520 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 722 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 29d100120e..66e34d8706 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -22,6 +23,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -34,6 +36,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..db65880d87
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,520 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "miscadmin.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints B-Tree index */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static GistCheckState gist_init_heapallindexed(Relation rel);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static GistCheckState
+gist_init_heapallindexed(Relation rel)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+	GistCheckState result;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = RelationGetNumberOfBlocks(rel);
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result.filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result.snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result.snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+	
+	return result;
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	if (heapallindexed)
+		check_state = gist_init_heapallindexed(rel);
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+	
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 * 
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.37.0 (Apple Git-136)

From a77ab4d265b9c19e14af2532a67191ec32746d1c Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v15 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 800 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 938 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..c914e6d0ba 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..d98d525c66
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 66e34d8706..f3f097c5c5 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..789259e662
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..90fe89501d
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,800 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "miscadmin.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state);
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.37.0 (Apple Git-136)

From fbf14a532dd21fa48521cb8978a05b6dc21c9c4f Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v15 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 ++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 306 ++++++++------------------------
 5 files changed, 296 insertions(+), 228 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 2194a91124..29d100120e 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,4 +1,5 @@
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 9021d156eb..950014f19d 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -41,6 +41,8 @@
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +140,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +184,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +208,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +236,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +255,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +320,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +692,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +774,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +992,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1028,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1341,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1634,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1644,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1764,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1868,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1919,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2006,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2238,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2262,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2311,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2681,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2804,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3042,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.37.0 (Apple Git-136)

From 653bad3f597e774f3d95070b8751d948581f9fa1 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v16 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 307 ++++++++------------------------
 5 files changed, 296 insertions(+), 229 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 2194a91124..29d100120e 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,4 +1,5 @@
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 9021d156eb..8c67edab2a 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -34,13 +34,14 @@
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.37.0 (Apple Git-136)

From bbb8f217eea72975d1ee6d895edca9c021669dde Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v16 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 798 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 936 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..c914e6d0ba 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..d98d525c66
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 66e34d8706..f3f097c5c5 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..789259e662
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..59aa860de6
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,798 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state);
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.37.0 (Apple Git-136)

From 2d938e125667e31f007d9bf20388ce5aee59b156 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v16 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 518 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 720 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 29d100120e..66e34d8706 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -22,6 +23,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -34,6 +36,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..f08e96f445
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,518 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints B-Tree index */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static GistCheckState gist_init_heapallindexed(Relation rel);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static GistCheckState
+gist_init_heapallindexed(Relation rel)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+	GistCheckState result;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = RelationGetNumberOfBlocks(rel);
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result.filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result.snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result.snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+
+	return result;
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	if (heapallindexed)
+		check_state = gist_init_heapallindexed(rel);
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.37.0 (Apple Git-136)

From bfdf8bd8267a37560db4bb5fd2f53164d23068df Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v17 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 538 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 740 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 29d100120e..66e34d8706 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -22,6 +23,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -34,6 +36,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..5a5fa73536
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,538 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState *result);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState *result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			  check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.37.0 (Apple Git-136)

From 9a24a686594058dc1cdc6ea70ec9adfe397a85b9 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v17 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 798 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 936 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..c914e6d0ba 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..d98d525c66
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 66e34d8706..f3f097c5c5 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,5 +1,6 @@
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..789259e662
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..c91fc11899
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,798 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state); // TODO, not implemented yet
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.37.0 (Apple Git-136)

From 653bad3f597e774f3d95070b8751d948581f9fa1 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v17 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 307 ++++++++------------------------
 5 files changed, 296 insertions(+), 229 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 2194a91124..29d100120e 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,4 +1,5 @@
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 9021d156eb..8c67edab2a 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -34,13 +34,14 @@
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.37.0 (Apple Git-136)

From 38f8cac157df49c079952eae3de3864f519fa958 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v18 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 798 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 936 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..c914e6d0ba 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..d98d525c66
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 45e9d74947..fec44a6826 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -39,6 +40,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..789259e662
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx', true);
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx', true);
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..c91fc11899
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,798 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	bool		heapallindexed = *((bool*)callback_state); // TODO, not implemented yet
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From 65733ff09b6133e630e4c1d5678cb66b48a3cbe2 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v18 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 538 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 740 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..45e9d74947 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..5a5fa73536
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,538 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState *result);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState *result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			  check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From 89a87b5239d0aabcc2208939f213df747c686f16 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v18 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 307 ++++++++------------------------
 5 files changed, 296 insertions(+), 229 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..3c1599f215 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -34,13 +34,14 @@
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.32.0 (Apple Git-132)

From 42bc27c4ed058ec24fe582d771989cbfa9a0b38b Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v19 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 793 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 931 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..5e283be45b 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 45e9d74947..fec44a6826 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -39,6 +40,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..8fd00513f7
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,793 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 9397a69c6e..7ffa36b205 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From 89a87b5239d0aabcc2208939f213df747c686f16 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v19 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 307 ++++++++------------------------
 5 files changed, 296 insertions(+), 229 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..3c1599f215 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -34,13 +34,14 @@
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.32.0 (Apple Git-132)

From 65733ff09b6133e630e4c1d5678cb66b48a3cbe2 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v19 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 538 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 740 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..45e9d74947 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..5a5fa73536
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,538 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState *result);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState *result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			  check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 5d61a33936..9397a69c6e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From e4d5ace7e8888a2fac4fa04f091fa2dd4ebf8342 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v20 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  27 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 307 ++++++++------------------------
 5 files changed, 296 insertions(+), 229 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..10906efd8a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..3c1599f215 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -34,13 +34,14 @@
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +139,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +183,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +207,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +235,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +254,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +319,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +691,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +773,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +991,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1027,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1340,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1633,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1643,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1763,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1867,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1918,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2005,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2237,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2261,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2310,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2680,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2803,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3041,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.32.0 (Apple Git-132)

From 7e758b4c5f97e250c201a0fc59b4b9420040558a Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v20 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 793 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 931 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..5e283be45b 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 45e9d74947..fec44a6826 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -39,6 +40,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..8fd00513f7
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,793 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index abe3135132..f472554ec7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From b7800362dd644654394e4d24ee18f7fb7cd39a73 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v20 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 538 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 740 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..45e9d74947 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..5a5fa73536
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,538 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState *result);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState *result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			  check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 923cbde9dd..abe3135132 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From b75c19ede76c40f5c3a0acdf36d462d9b60aef8b Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v21 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/amcheck.c              |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 793 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 8 files changed, 931 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index a817419581..ecb849a605 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -5,6 +5,7 @@ OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
 	verify_gist.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
@@ -14,7 +15,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap check_gist
+REGRESS = check check_btree check_heap check_gist check_gin
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379ef..5e283be45b 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 3793b0cd93..9999a233f8 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -83,7 +83,7 @@ amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
 	else
 	{
 		heaprel = NULL;
-		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		/* Set these just to suppress "uninitialized variable" warnings */
 		save_userid = InvalidOid;
 		save_sec_context = -1;
 		save_nestlevel = -1;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 45e9d74947..fec44a6826 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -39,6 +40,7 @@ tests += {
       'check_btree',
       'check_heap',
       'check_gist',
+      'check_gin',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..8fd00513f7
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,793 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state);
+static bool check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel, BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid, gin_index_checkable,
+		gin_check_parent_keys_consistency, AccessShareLock, NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			} else {
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 &&
+				ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			}
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			int			lowersize;
+			ItemPointerData bound;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno,
+					 maxoff,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items", stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff).
+			 * Make sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was binary-upgraded
+			 * from an earlier version. That was a long time ago, though, so let's
+			 * warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+			}
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				if (!ItemPointerEquals(&stack->parentkey, &bound))
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+									RelationGetRelationName(rel),
+									ItemPointerGetBlockNumberNoCheck(&bound),
+									ItemPointerGetOffsetNumberNoCheck(&bound),
+									stack->blkno,
+									stack->parentblk,
+									ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+									ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+				}
+			}
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/* The rightmost item in the tree level has (0, 0) as the key */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+					}
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff)
+				{
+					if (ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+
+					}
+				}
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		if (!check_index_page(rel, buffer, stack->blkno))
+		{
+			goto nextpage;
+		}
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, maxoff, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key, page_max_key_category, parent_key, parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+				goto nextpage;
+			}
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GinPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			{
+				ereport(WARNING,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+				continue;
+			}
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key, prev_key_category, current_key, current_key_category) >= 0)
+				{
+					ereport(WARNING,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				}
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state, stack->parenttup, &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key, current_key_category, parent_key, parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+					{
+						ereport(WARNING,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+					}
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+nextpage:
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static bool
+gincheckpage(Relation rel, Buffer buf)
+{
+	Page		page = BufferGetPage(buf);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buf)),
+				 errhint("Please REINDEX it.")));
+		return false;
+	}
+	return true;
+}
+
+static bool
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	if (!gincheckpage(rel, buffer))
+		return false;
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+		{
+			ereport(WARNING,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+			return false;
+		}
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+	{
+		ereport(WARNING,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+		return false;
+	}
+	return true;
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GinPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index abe3135132..f472554ec7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From a5a92975e2fac3e306d9ffb339dae0301996e444 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v21 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   2 +
 contrib/amcheck/amcheck.c       | 188 +++++++++++++++++++
 contrib/amcheck/amcheck.h       |  29 +++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 308 ++++++++------------------------
 5 files changed, 298 insertions(+), 230 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..f10fd9d89d 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,11 +3,13 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
 DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
 REGRESS = check check_btree check_heap
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..3793b0cd93
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,188 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool
+amcheck_index_mainfork_expected(Relation rel);
+
+/*
+ * Check if index relation should have a file for its main relation
+ * fork.  Verification uses this to skip unlogged indexes when in hot standby
+ * mode, where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable()
+ * before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid, IndexCheckableCallback checkable,
+												IndexDoCheckCallback check, LOCKMODE lockmode, void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* for "gcc -Og" https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78394 */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * PageGetItemId() wrapper that validates returned line pointer.
+ *
+ * Buffer page/page item access macros generally trust that line pointers are
+ * not corrupt, which might cause problems for verification itself.  For
+ * example, there is no bounds checking in PageGetItem().  Passing it a
+ * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
+ * to dereference.
+ *
+ * Validating line pointers before tuples avoids undefined behavior and
+ * assertion failures with corrupt indexes, making the verification process
+ * more robust and predictable.
+ */
+ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset, size_t opaquesize)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	Assert(opaquesize == MAXALIGN(opaquesize));
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(opaquesize))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree and gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..fac9511f0b
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,29 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel, Relation heaprel, void* state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+					 Page page, OffsetNumber offset, size_t opaquesize);
\ No newline at end of file
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..37a8e957de 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -34,13 +34,13 @@
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "utils/snapmgr.h"
 
+#include "amcheck.h"
+
 
 PG_MODULE_MAGIC;
 
@@ -138,10 +138,8 @@ typedef struct BtreeLevel
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -184,12 +182,17 @@ static inline bool invariant_l_nontarget_offset(BtreeCheckState *state,
 static Page palloc_btree_page(BtreeCheckState *state, BlockNumber blocknum);
 static inline BTScanInsert bt_mkscankey_pivotsearch(Relation rel,
 													IndexTuple itup);
-static ItemId PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block,
-								   Page page, OffsetNumber offset);
 static inline ItemPointer BTreeTupleGetHeapTIDCareful(BtreeCheckState *state,
 													  IndexTuple itup, bool nonpivot);
 static inline ItemPointer BTreeTupleGetPointsToTID(IndexTuple itup);
 
+typedef struct BTCheckCallbackState
+{
+	bool parentcheck;
+	bool heapallindexed;
+	bool rootdescend;
+} BTCheckCallbackState;
+
 /*
  * bt_index_check(index regclass, heapallindexed boolean)
  *
@@ -203,12 +206,17 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCheckCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +234,18 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCheckCallbackState args;
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+		bt_index_check_internal_callback, ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -242,126 +253,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
 /*
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
-static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+static void bt_index_check_internal_callback(Relation indrel, Relation heaprel, void* state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCheckCallbackState* args = (BTCheckCallbackState*) state;
+	bool		heapkeyspace,
+					allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+							args->heapallindexed, args->rootdescend);
 
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +318,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
@@ -793,9 +690,9 @@ bt_check_level_from_leftmost(BtreeCheckState *state, BtreeLevel level)
 				ItemId		itemid;
 
 				/* Internal page -- downlink gets leftmost on next level */
-				itemid = PageGetItemIdCareful(state, state->targetblock,
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 											  state->target,
-											  P_FIRSTDATAKEY(opaque));
+											  P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 				nextleveldown.leftmost = BTreeTupleGetDownLink(itup);
 				nextleveldown.level = opaque->btpo_level - 1;
@@ -875,8 +772,8 @@ nextpage:
 			IndexTuple	itup;
 			ItemId		itemid;
 
-			itemid = PageGetItemIdCareful(state, state->targetblock,
-										  state->target, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+										  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 
 			state->lowkey = MemoryContextAlloc(oldcontext, IndexTupleSize(itup));
@@ -1093,8 +990,8 @@ bt_target_page_check(BtreeCheckState *state)
 		IndexTuple	itup;
 
 		/* Verify line pointer before checking tuple */
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, P_HIKEY, sizeof(BTPageOpaqueData));
 		if (!_bt_check_natts(state->rel, state->heapkeyspace, state->target,
 							 P_HIKEY))
 		{
@@ -1129,8 +1026,8 @@ bt_target_page_check(BtreeCheckState *state)
 
 		CHECK_FOR_INTERRUPTS();
 
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, offset);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, offset, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		tupsize = IndexTupleSize(itup);
 
@@ -1442,9 +1339,9 @@ bt_target_page_check(BtreeCheckState *state)
 							 OffsetNumberNext(offset));
 
 			/* Reuse itup to get pointed-to heap location of second item */
-			itemid = PageGetItemIdCareful(state, state->targetblock,
+			itemid = PageGetItemIdCareful(state->rel, state->targetblock,
 										  state->target,
-										  OffsetNumberNext(offset));
+										  OffsetNumberNext(offset), sizeof(BTPageOpaqueData));
 			itup = (IndexTuple) PageGetItem(state->target, itemid);
 			tid = BTreeTupleGetPointsToTID(itup);
 			nhtid = psprintf("(%u,%u)",
@@ -1735,8 +1632,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 	if (P_ISLEAF(opaque) && nline >= P_FIRSTDATAKEY(opaque))
 	{
 		/* Return first data item (if any) */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 P_FIRSTDATAKEY(opaque));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	}
 	else if (!P_ISLEAF(opaque) &&
 			 nline >= OffsetNumberNext(P_FIRSTDATAKEY(opaque)))
@@ -1745,8 +1642,8 @@ bt_right_page_check_scankey(BtreeCheckState *state)
 		 * Return first item after the internal page's "negative infinity"
 		 * item
 		 */
-		rightitem = PageGetItemIdCareful(state, targetnext, rightpage,
-										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)));
+		rightitem = PageGetItemIdCareful(state->rel, targetnext, rightpage,
+										 OffsetNumberNext(P_FIRSTDATAKEY(opaque)), sizeof(BTPageOpaqueData));
 	}
 	else
 	{
@@ -1865,8 +1762,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 
 	if (OffsetNumberIsValid(target_downlinkoffnum))
 	{
-		itemid = PageGetItemIdCareful(state, state->targetblock,
-									  state->target, target_downlinkoffnum);
+		itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+									  state->target, target_downlinkoffnum, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(state->target, itemid);
 		downlink = BTreeTupleGetDownLink(itup);
 	}
@@ -1969,7 +1866,7 @@ bt_child_highkey_check(BtreeCheckState *state,
 			OffsetNumber pivotkey_offset;
 
 			/* Get high key */
-			itemid = PageGetItemIdCareful(state, blkno, page, P_HIKEY);
+			itemid = PageGetItemIdCareful(state->rel, blkno, page, P_HIKEY, sizeof(BTPageOpaqueData));
 			highkey = (IndexTuple) PageGetItem(page, itemid);
 
 			/*
@@ -2020,8 +1917,8 @@ bt_child_highkey_check(BtreeCheckState *state,
 													LSN_FORMAT_ARGS(state->targetlsn))));
 					pivotkey_offset = P_HIKEY;
 				}
-				itemid = PageGetItemIdCareful(state, state->targetblock,
-											  state->target, pivotkey_offset);
+				itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+											  state->target, pivotkey_offset, sizeof(BTPageOpaqueData));
 				itup = (IndexTuple) PageGetItem(state->target, itemid);
 			}
 			else
@@ -2107,8 +2004,8 @@ bt_child_check(BtreeCheckState *state, BTScanInsert targetkey,
 	BTPageOpaque copaque;
 	BTPageOpaque topaque;
 
-	itemid = PageGetItemIdCareful(state, state->targetblock,
-								  state->target, downlinkoffnum);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock,
+								  state->target, downlinkoffnum, sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(state->target, itemid);
 	childblock = BTreeTupleGetDownLink(itup);
 
@@ -2339,7 +2236,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 		 RelationGetRelationName(state->rel));
 
 	level = opaque->btpo_level;
-	itemid = PageGetItemIdCareful(state, blkno, page, P_FIRSTDATAKEY(opaque));
+	itemid = PageGetItemIdCareful(state->rel, blkno, page, P_FIRSTDATAKEY(opaque), sizeof(BTPageOpaqueData));
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	childblk = BTreeTupleGetDownLink(itup);
 	for (;;)
@@ -2363,8 +2260,8 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 										level - 1, copaque->btpo_level)));
 
 		level = copaque->btpo_level;
-		itemid = PageGetItemIdCareful(state, childblk, child,
-									  P_FIRSTDATAKEY(copaque));
+		itemid = PageGetItemIdCareful(state->rel, childblk, child,
+									  P_FIRSTDATAKEY(copaque), sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		childblk = BTreeTupleGetDownLink(itup);
 		/* Be slightly more pro-active in freeing this memory, just in case */
@@ -2412,7 +2309,7 @@ bt_downlink_missing_check(BtreeCheckState *state, bool rightsplit,
 	 */
 	if (P_ISHALFDEAD(copaque) && !P_RIGHTMOST(copaque))
 	{
-		itemid = PageGetItemIdCareful(state, childblk, child, P_HIKEY);
+		itemid = PageGetItemIdCareful(state->rel, childblk, child, P_HIKEY, sizeof(BTPageOpaqueData));
 		itup = (IndexTuple) PageGetItem(child, itemid);
 		if (BTreeTupleGetTopParent(itup) == blkno)
 			return;
@@ -2782,8 +2679,8 @@ invariant_l_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, state->targetblock, state->target,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, state->targetblock, state->target,
+								  upperbound, sizeof(BTPageOpaqueData));
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
 	if (!key->heapkeyspace)
 		return invariant_leq_offset(state, key, upperbound);
@@ -2905,8 +2802,8 @@ invariant_l_nontarget_offset(BtreeCheckState *state, BTScanInsert key,
 	Assert(key->pivotsearch);
 
 	/* Verify line pointer before checking tuple */
-	itemid = PageGetItemIdCareful(state, nontargetblock, nontarget,
-								  upperbound);
+	itemid = PageGetItemIdCareful(state->rel, nontargetblock, nontarget,
+								  upperbound, sizeof(BTPageOpaqueData));
 	cmp = _bt_compare(state->rel, key, nontarget, upperbound);
 
 	/* pg_upgrade'd indexes may legally have equal sibling tuples */
@@ -3143,55 +3040,6 @@ bt_mkscankey_pivotsearch(Relation rel, IndexTuple itup)
 	return skey;
 }
 
-/*
- * PageGetItemId() wrapper that validates returned line pointer.
- *
- * Buffer page/page item access macros generally trust that line pointers are
- * not corrupt, which might cause problems for verification itself.  For
- * example, there is no bounds checking in PageGetItem().  Passing it a
- * corrupt line pointer can cause it to return a tuple/pointer that is unsafe
- * to dereference.
- *
- * Validating line pointers before tuples avoids undefined behavior and
- * assertion failures with corrupt indexes, making the verification process
- * more robust and predictable.
- */
-static ItemId
-PageGetItemIdCareful(BtreeCheckState *state, BlockNumber block, Page page,
-					 OffsetNumber offset)
-{
-	ItemId		itemid = PageGetItemId(page, offset);
-
-	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
-		BLCKSZ - MAXALIGN(sizeof(BTPageOpaqueData)))
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("line pointer points past end of tuple space in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	/*
-	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
-	 * never uses either.  Verify that line pointer has storage, too, since
-	 * even LP_DEAD items should within nbtree.
-	 */
-	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
-		ItemIdGetLength(itemid) == 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_INDEX_CORRUPTED),
-				 errmsg("invalid line pointer storage in index \"%s\"",
-						RelationGetRelationName(state->rel)),
-				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
-									block, offset, ItemIdGetOffset(itemid),
-									ItemIdGetLength(itemid),
-									ItemIdGetFlags(itemid))));
-
-	return itemid;
-}
-
 /*
  * BTreeTupleGetHeapTID() wrapper that enforces that a heap TID is present in
  * cases where that is mandatory (i.e. for non-pivot tuples)
-- 
2.32.0 (Apple Git-132)

From ca68e194f462cdd95b74c80106c02ba34f6f07aa Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v21 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 ++++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 538 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 740 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f10fd9d89d..a817419581 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,15 +4,17 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_heap check_gist
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..93297379ef
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..9749adfd34
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..45e9d74947 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
       'check',
       'check_btree',
       'check_heap',
+      'check_gist',
     ],
   },
   'tap': {
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..75b9ff4b43
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..5a5fa73536
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,538 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "catalog/index.h"
+#include "lib/bloomfilter.h"
+#include "storage/lmgr.h"
+#include "storage/smgr.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+#include "amcheck.h"
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE      *state;
+
+	Snapshot		snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState *result);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+												void* callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid		indrelid = PG_GETARG_OID(0);
+	bool	heapallindexed = false;
+
+	if (PG_NARGS() >= 2)
+		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, gist_index_checkable,
+		gist_check_parent_keys_consistency, AccessShareLock, &heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState *result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index.
+	 * This logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+						(int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in
+	 * READ COMMITTED mode.  A new snapshot is guaranteed to have all
+	 * the entries it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact
+	 * snapshot was returned at higher isolation levels when that
+	 * snapshot is not safe for index scans of the target index.  This
+	 * is possible when the snapshot sees tuples that are before the
+	 * index's indcheckxmin horizon.  Throwing an error here should be
+	 * very rare.  It doesn't seem worth using a secondary snapshot to
+	 * avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+								result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+					errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel, void* callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem   *stack;
+	MemoryContext	mctx;
+	MemoryContext	oldcontext;
+	GISTSTATE      *state;
+	int				leafdepth;
+	bool			heapallindexed = *((bool*)callback_state);
+	GistCheckState  check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber  i, maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			  check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno, page, i, sizeof(GISTPageOpaqueData));
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples.
+				 * We need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+				{
+					bloom_add_element(check_state.filter, (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+				}
+			}
+			/* If this is an internal page, recurse into the child */
+			else
+			{
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+		(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+							check_state.heaptuplespresent, RelationGetRelationName(heaprel),
+							100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+						  bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel, BlockNumber parentblkno,
+				   BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o, sizeof(GISTPageOpaqueData));
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 923cbde9dd..abe3135132 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From 855c21e319fd44c87870ccd2af120c7ae40a969d Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v22 2/3] Add gist_index_parent_check() function to verify GiST
 index

---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 576 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 778 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 6d26551fe..e9e019827 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 000000000..93297379e
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_parent_check()
+--
+CREATE FUNCTION gist_index_parent_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f7..e67ace01c 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 000000000..9749adfd3
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', false);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx1', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+SELECT gist_index_parent_check('gist_check_idx2', true);
+ gist_index_parent_check 
+-------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3b..9e7ebc049 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -35,6 +37,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 000000000..75b9ff4b4
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_parent_check('gist_check_idx1', false);
+SELECT gist_index_parent_check('gist_check_idx2', false);
+SELECT gist_index_parent_check('gist_check_idx1', true);
+SELECT gist_index_parent_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 000000000..845d87ee8
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,576 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_parent_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_index_checkable(Relation rel);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_parent_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									gist_index_checkable,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Check that relation is eligible for GiST verification
+ */
+static void
+gist_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIST_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GiST indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GiST index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph.  This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	int			leafdepth;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples. We
+				 * need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+					bloom_add_element(check_state.filter,
+									  (unsigned char *) idxtuple,
+									  IndexTupleSize(idxtuple));
+			}
+			else
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state.heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 2b9c1a920..41f7e952e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_parent_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.39.0

From 71e01bbb51c112cd36fccf5be0b923633d31831d Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v22 1/3] Refactor amcheck to extract common locking routines

---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 139 ++++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  28 +++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 202 +++++++++-----------------------
 5 files changed, 222 insertions(+), 149 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e5..6d26551fe 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 000000000..2a2782f4b
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,139 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								IndexCheckableCallback checkable,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	checkable(indrel);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 000000000..4630426d1
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,28 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											IndexCheckableCallback checkable,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343..cd81cbf3b 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671..6c90d01f8 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -29,13 +29,12 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -135,13 +134,20 @@ typedef struct BtreeLevel
 	bool		istruerootlevel;
 } BtreeLevel;
 
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+} BTCallbackState;
+
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state);
 static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -203,12 +209,18 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +238,20 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, btree_index_checkable,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -243,125 +260,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+						 args->heapallindexed, args->rootdescend);
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
 }
 
 /*
@@ -398,29 +325,6 @@ btree_index_checkable(Relation rel)
 				 errdetail("Index is not valid.")));
 }
 
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
-}
-
 /*
  * Main entry point for B-Tree SQL-callable functions. Walks the B-Tree in
  * logical order, verifying invariants as it goes.  Optionally, verification
-- 
2.39.0

From ce7c009b9d7abcb41f9f79c1216d7001cfbc2c4f Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v22 3/3] Add gin_index_parent_check() to verify GIN index

---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 799 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 936 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index e9e019827..4c672f0db 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 93297379e..5e283be45 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_parent_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_parent_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 000000000..43fd769a5
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 9e7ebc049..dc2191bd5 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 000000000..9771afffa
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 000000000..ee4696e68
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,799 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_index_checkable(Relation rel);
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									gin_index_checkable,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+
+/*
+ * Check that relation is eligible for GIN verification
+ */
+static void
+gin_index_checkable(Relation rel)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != GIN_AM_OID)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only GIN indexes are supported as targets for this verification"),
+				 errdetail("Relation \"%s\" is not a GIN index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid")));
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 41f7e952e..5549c0173 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_parent_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.39.0

From d45ce69e9d15e5da36ca651d7c6ca46cd84399f2 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v23 1/3] Refactor amcheck to extract common locking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 ++++++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  30 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 233 +++++++-------------------------
 5 files changed, 256 insertions(+), 182 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..6d26551fe3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..5a9c9429a3
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"),
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..b139da067a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..c2ae2cb011 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -29,13 +29,12 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -135,13 +134,19 @@ typedef struct BtreeLevel
 	bool		istruerootlevel;
 } BtreeLevel;
 
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+} BTCallbackState;
+
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -203,12 +208,18 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +237,20 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -243,182 +259,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+						 args->heapallindexed, args->rootdescend);
 
-	return false;
 }
 
 /*
-- 
2.32.0 (Apple Git-132)

From 3b6b704f2236e0bc3a08d7173a57aec8de9207a5 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v23 2/3] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 581 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 783 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 6d26551fe3..e9e0198276 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..5d30784b44
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..4f3baa3776
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..9e7ebc0499 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -35,6 +37,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..0e3a8cf3bb
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..9776969b4c
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,581 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	int			leafdepth;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples. We
+				 * need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+					bloom_add_element(check_state.filter,
+									  (unsigned char *) idxtuple,
+									  IndexTupleSize(idxtuple));
+			}
+			else
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state.heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* That's somewhat suspicious - parent page converted to leaf? */
+		/* Anyway, it's definitely not a page we were looking for */
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 2b9c1a9205..40de7c33f5 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From 980d497e5c8d13431c73701190eb6ec4d069f385 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v23 3/3] Add gin_index_parent_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 768 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index e9e0198276..4c672f0db8 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 5d30784b44..ca985fff2e 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 9e7ebc0499..dc2191bd59 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..af9ace2f33
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,768 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 40de7c33f5..e5c8d84db9 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From 7d896c762ca82f2740c7d780f41dffb402ff8610 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v24 4/4] Add GiST support to pg_amcheck

---
 src/bin/pg_amcheck/pg_amcheck.c      | 205 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  48 ++++---
 3 files changed, 157 insertions(+), 104 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 68f8180c19..fad6350cd2 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,7 +73,7 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
+	 * tables, or similarly if any such pattern applies to indexes, or
 	 * to schemas, then these will be true, otherwise false.  These should
 	 * always agree with what you'd conclude by grep'ing through the exclude
 	 * list.
@@ -98,13 +97,13 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -132,7 +131,7 @@ static AmcheckOptions opts = {
 	.parent_check = false,
 	.rootdescend = false,
 	.heapallindexed = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -154,7 +153,8 @@ typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -175,10 +175,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								  PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -192,7 +194,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -318,11 +320,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -377,7 +379,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -609,8 +611,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -743,13 +745,20 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+				prepare_gist_command(&sql, rel, free_slot->connection);
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+					 		rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -827,7 +836,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -869,6 +878,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+						"SELECT %s.gist_index_check("
+						"index := c.oid, heapallindexed := %s)"
+						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+						"WHERE c.oid = %u "
+						"AND c.oid = i.indexrelid "
+						"AND c.relpersistence != 't' "
+						"AND i.indisready AND i.indisvalid AND i.indislive",
+						rel->datinfo->amcheck_schema,
+						(opts.heapallindexed ? "true" : "false"),
+						rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -908,7 +939,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1057,11 +1088,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1070,7 +1101,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1081,7 +1112,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
+			 * We expect the checking functions to return one void row
 			 * each, or zero rows if the check was skipped due to the object
 			 * being in the wrong state to be checked, so we should output
 			 * some sort of warning if we get anything more, not because it
@@ -1096,7 +1127,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1110,7 +1141,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1163,6 +1194,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1376,11 +1409,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1415,14 +1448,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1451,17 +1484,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1719,7 +1752,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1761,7 +1794,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1799,8 +1832,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1823,7 +1856,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1850,7 +1883,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1860,7 +1893,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1868,36 +1901,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1931,12 +1964,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -1965,17 +1998,18 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
 		 * selected above, filtering by exclusion patterns (if any) that match
-		 * btree index names.
+		 * btree index names. Currently, only btree indexes can be PK, but this
+		 * might chance in future.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -1988,7 +2022,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -1996,7 +2030,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBuffer(&sql,
 						  " AND c.relam = %u "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID); /* Do not expect other AMs here */
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2004,7 +2038,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2025,13 +2059,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2045,12 +2079,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2059,29 +2094,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Toast tables for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
+							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
 							 "FROM toast");
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Indexes for toast relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+							 "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2101,8 +2136,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2112,15 +2148,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2142,10 +2180,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2155,7 +2194,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 58be2c694d..5e8a63a844 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -319,8 +319,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 359abe25a1..8b6326dd3d 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -288,22 +288,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -434,10 +436,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
-- 
2.32.0 (Apple Git-132)

From d45ce69e9d15e5da36ca651d7c6ca46cd84399f2 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v24 1/4] Refactor amcheck to extract common locking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 ++++++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  30 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 233 +++++++-------------------------
 5 files changed, 256 insertions(+), 182 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..6d26551fe3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..5a9c9429a3
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"),
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..b139da067a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..c2ae2cb011 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -29,13 +29,12 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -135,13 +134,19 @@ typedef struct BtreeLevel
 	bool		istruerootlevel;
 } BtreeLevel;
 
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+} BTCallbackState;
+
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -203,12 +208,18 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +237,20 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -243,182 +259,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+						 args->heapallindexed, args->rootdescend);
 
-	return false;
 }
 
 /*
-- 
2.32.0 (Apple Git-132)

From 3b6b704f2236e0bc3a08d7173a57aec8de9207a5 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v24 2/4] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 581 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 783 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 6d26551fe3..e9e0198276 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..5d30784b44
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..4f3baa3776
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..9e7ebc0499 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -35,6 +37,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..0e3a8cf3bb
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..9776969b4c
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,581 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	int			leafdepth;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState check_state;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state.state = state;
+	check_state.rel = rel;
+	check_state.heaprel = heaprel;
+
+	check_state.totalblocks = RelationGetNumberOfBlocks(rel);
+	check_state.reportedblocks = 0;
+	check_state.scannedblocks = 0;
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state.deltablocks = Max(check_state.totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, &check_state);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state.scannedblocks > check_state.reportedblocks +
+			check_state.deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state.scannedblocks, check_state.totalblocks);
+			check_state.reportedblocks = check_state.scannedblocks;
+		}
+		check_state.scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GistPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that each tuple looks valid, and is consistent with the
+		 * downlink we followed when we stepped on this page.
+		 */
+		maxoff = PageGetMaxOffsetNumber(page);
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+			/*
+			 * Check that it's not a leftover invalid tuple from pre-9.1 See
+			 * also gistdoinsert() and gistbulkdelete() handling of such
+			 * tuples. We do consider it error here.
+			 */
+			if (GistTupleIsInvalid(idxtuple))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i),
+						 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						 errhint("Please REINDEX it.")));
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+			{
+				/*
+				 * There was a discrepancy between parent and child tuples. We
+				 * need to verify it is not a result of concurrent call of
+				 * gistplacetopage(). So, lock parent and try to find downlink
+				 * for current page. It may be missing due to concurrent page
+				 * split, this is OK.
+				 *
+				 * Note that when we aquire parent tuple now we hold lock for
+				 * both parent and child buffers. Thus parent tuple must
+				 * include keyspace of the child.
+				 */
+				pfree(stack->parenttup);
+				stack->parenttup = gist_refind_parent(rel, stack->parentblk,
+													  stack->blkno, strategy);
+
+				/* We found it - make a final check before failing */
+				if (!stack->parenttup)
+					elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						 stack->blkno, stack->parentblk);
+				else if (gistgetadjusted(rel, stack->parenttup, idxtuple, state))
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+				else
+				{
+					/*
+					 * But now it is properly adjusted - nothing to do here.
+					 */
+				}
+			}
+
+			if (GistPageIsLeaf(page))
+			{
+				if (heapallindexed)
+					bloom_add_element(check_state.filter,
+									  (unsigned char *) idxtuple,
+									  IndexTupleSize(idxtuple));
+			}
+			else
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state.snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) &check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state.heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state.filter))));
+
+		UnregisterSnapshot(check_state.snapshot);
+		bloom_free(check_state.filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* That's somewhat suspicious - parent page converted to leaf? */
+		/* Anyway, it's definitely not a page we were looking for */
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 2b9c1a9205..40de7c33f5 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From 980d497e5c8d13431c73701190eb6ec4d069f385 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v24 3/4] Add gin_index_parent_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 768 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index e9e0198276..4c672f0db8 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 5d30784b44..ca985fff2e 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 9e7ebc0499..dc2191bd59 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..af9ace2f33
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,768 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 40de7c33f5..e5c8d84db9 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From 648e34451c0d296a8058d28bb4357d77876cb082 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v25 3/4] Add gin_index_parent_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 768 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index e9e0198276..4c672f0db8 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 5d30784b44..ca985fff2e 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 9e7ebc0499..dc2191bd59 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..af9ace2f33
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,768 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 40de7c33f5..e5c8d84db9 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.32.0 (Apple Git-132)

From 1323d72f29adbc78a5ea3ff66b956b6c7272cbd5 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v25 4/4] Add GiST support to pg_amcheck

---
 src/bin/pg_amcheck/pg_amcheck.c      | 205 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  48 ++++---
 3 files changed, 157 insertions(+), 104 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 68f8180c19..337399539d 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,7 +73,7 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
+	 * tables, or similarly if any such pattern applies to indexes, or
 	 * to schemas, then these will be true, otherwise false.  These should
 	 * always agree with what you'd conclude by grep'ing through the exclude
 	 * list.
@@ -98,13 +97,13 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -132,7 +131,7 @@ static AmcheckOptions opts = {
 	.parent_check = false,
 	.rootdescend = false,
 	.heapallindexed = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -154,7 +153,8 @@ typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -175,10 +175,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								  PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -192,7 +194,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -318,11 +320,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -377,7 +379,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -609,8 +611,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -743,13 +745,20 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+				prepare_gist_command(&sql, rel, free_slot->connection);
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -827,7 +836,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -869,6 +878,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+						"SELECT %s.gist_index_check("
+						"index := c.oid, heapallindexed := %s)"
+						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+						"WHERE c.oid = %u "
+						"AND c.oid = i.indexrelid "
+						"AND c.relpersistence != 't' "
+						"AND i.indisready AND i.indisvalid AND i.indislive",
+						rel->datinfo->amcheck_schema,
+						(opts.heapallindexed ? "true" : "false"),
+						rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -908,7 +939,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1057,11 +1088,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1070,7 +1101,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1081,7 +1112,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
+			 * We expect the checking functions to return one void row
 			 * each, or zero rows if the check was skipped due to the object
 			 * being in the wrong state to be checked, so we should output
 			 * some sort of warning if we get anything more, not because it
@@ -1096,7 +1127,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1110,7 +1141,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1163,6 +1194,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1376,11 +1409,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1415,14 +1448,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1451,17 +1484,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1719,7 +1752,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1761,7 +1794,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1799,8 +1832,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1823,7 +1856,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1850,7 +1883,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1860,7 +1893,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1868,36 +1901,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1931,12 +1964,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -1965,17 +1998,18 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
 		 * selected above, filtering by exclusion patterns (if any) that match
-		 * btree index names.
+		 * btree index names. Currently, only btree indexes can be PK, but this
+		 * might chance in future.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -1988,7 +2022,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -1996,7 +2030,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBuffer(&sql,
 						  " AND c.relam = %u "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID); /* Do not expect other AMs here */
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2004,7 +2038,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2025,13 +2059,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2045,12 +2079,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2059,29 +2094,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Toast tables for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
+							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
 							 "FROM toast");
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Indexes for toast relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+							 "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2101,8 +2136,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2112,15 +2148,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2142,10 +2180,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2155,7 +2194,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 58be2c694d..5e8a63a844 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -319,8 +319,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 359abe25a1..8b6326dd3d 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -288,22 +288,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -434,10 +436,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
-- 
2.32.0 (Apple Git-132)

From 9dd36253feb5a213a014a61d2e8e7d8cddc3e585 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v25 1/4] Refactor amcheck to extract common locking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 ++++++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  30 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 233 +++++++-------------------------
 5 files changed, 256 insertions(+), 182 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..6d26551fe3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..5a9c9429a3
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"),
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..b139da067a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..c2ae2cb011 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -29,13 +29,12 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -135,13 +134,19 @@ typedef struct BtreeLevel
 	bool		istruerootlevel;
 } BtreeLevel;
 
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+} BTCallbackState;
+
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -203,12 +208,18 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +237,20 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -243,182 +259,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+						 args->heapallindexed, args->rootdescend);
 
-	return false;
 }
 
 /*
-- 
2.32.0 (Apple Git-132)

From 33d273cd74afa035c60a64460a83eb52c4c32951 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v25 2/4] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 119 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  42 ++
 contrib/amcheck/verify_gist.c           | 607 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 809 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 6d26551fe3..e9e0198276 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..5d30784b44
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..4f3baa3776
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,119 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..9e7ebc0499 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -35,6 +37,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..0e3a8cf3bb
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,42 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..dda37e8b27
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,607 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int leafdepth;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state);
+static void gist_check_page(GistCheckState *check_state,GistScanItem *stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+							Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the
+	 * downlink we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See
+		 * also gistdoinsert() and gistbulkdelete() handling of such
+		 * tuples. We do consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+						errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the
+		 * parent.
+		 */
+		if (stack->parenttup &&
+			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink
+			 * for current page. It may be missing due to concurrent page
+			 * split, this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for
+			 * both parent and child buffers. Thus parent tuple must
+			 * include keyspace of the child.
+			 */
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+													stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+									(unsigned char *) idxtuple,
+									IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormTuple(state->state, index, values, isnull, true);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* 
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf 
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 2b9c1a9205..40de7c33f5 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.32.0 (Apple Git-132)

From 9dd36253feb5a213a014a61d2e8e7d8cddc3e585 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v26 1/4] Refactor amcheck to extract common locking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 ++++++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  30 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 233 +++++++-------------------------
 5 files changed, 256 insertions(+), 182 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index b82f221e50..6d26551fe3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..5a9c9429a3
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"),
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..b139da067a
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5b55cf343a..cd81cbf3bc 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2023, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 257cff671b..c2ae2cb011 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -29,13 +29,12 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -135,13 +134,19 @@ typedef struct BtreeLevel
 	bool		istruerootlevel;
 } BtreeLevel;
 
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+} BTCallbackState;
+
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend);
@@ -203,12 +208,18 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
+	BTCallbackState args;
 
-	if (PG_NARGS() == 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false);
+	if (PG_NARGS() >= 2)
+		args.heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -226,15 +237,20 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() == 3)
-		rootdescend = PG_GETARG_BOOL(2);
+		args.rootdescend = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -243,182 +259,35 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
-
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
-	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel))));
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend);
-	}
-
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel))));
 
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, args->parentcheck,
+						 args->heapallindexed, args->rootdescend);
 
-	return false;
 }
 
 /*
-- 
2.37.1 (Apple Git-137.1)

From 5b244859b96ca4f236c529b8384fe8ea8ad7eec6 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v26 3/4] Add gin_index_parent_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.3--1.4.sql  |  11 +-
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 768 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index e9e0198276..4c672f0db8 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
index 5d30784b44..ca985fff2e 100644
--- a/contrib/amcheck/amcheck--1.3--1.4.sql
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -11,4 +11,13 @@ RETURNS VOID
 AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
-REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 9e7ebc0499..dc2191bd59 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -37,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..af9ace2f33
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,768 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 40de7c33f5..e5c8d84db9 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -180,6 +180,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.37.1 (Apple Git-137.1)

From 240f4f42242216794e3348d8027b3ae6abe4f02b Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v26 4/4] Add GiST support to pg_amcheck

---
 src/bin/pg_amcheck/pg_amcheck.c      | 205 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  48 ++++---
 3 files changed, 157 insertions(+), 104 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 68f8180c19..337399539d 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,7 +73,7 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
+	 * tables, or similarly if any such pattern applies to indexes, or
 	 * to schemas, then these will be true, otherwise false.  These should
 	 * always agree with what you'd conclude by grep'ing through the exclude
 	 * list.
@@ -98,13 +97,13 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -132,7 +131,7 @@ static AmcheckOptions opts = {
 	.parent_check = false,
 	.rootdescend = false,
 	.heapallindexed = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -154,7 +153,8 @@ typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -175,10 +175,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								  PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -192,7 +194,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -318,11 +320,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -377,7 +379,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -609,8 +611,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -743,13 +745,20 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+				prepare_gist_command(&sql, rel, free_slot->connection);
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -827,7 +836,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -869,6 +878,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+						"SELECT %s.gist_index_check("
+						"index := c.oid, heapallindexed := %s)"
+						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+						"WHERE c.oid = %u "
+						"AND c.oid = i.indexrelid "
+						"AND c.relpersistence != 't' "
+						"AND i.indisready AND i.indisvalid AND i.indislive",
+						rel->datinfo->amcheck_schema,
+						(opts.heapallindexed ? "true" : "false"),
+						rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -908,7 +939,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1057,11 +1088,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1070,7 +1101,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1081,7 +1112,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
+			 * We expect the checking functions to return one void row
 			 * each, or zero rows if the check was skipped due to the object
 			 * being in the wrong state to be checked, so we should output
 			 * some sort of warning if we get anything more, not because it
@@ -1096,7 +1127,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1110,7 +1141,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1163,6 +1194,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1376,11 +1409,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1415,14 +1448,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1451,17 +1484,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1719,7 +1752,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1761,7 +1794,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1799,8 +1832,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1823,7 +1856,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1850,7 +1883,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1860,7 +1893,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1868,36 +1901,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1931,12 +1964,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -1965,17 +1998,18 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
 		 * selected above, filtering by exclusion patterns (if any) that match
-		 * btree index names.
+		 * btree index names. Currently, only btree indexes can be PK, but this
+		 * might chance in future.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -1988,7 +2022,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -1996,7 +2030,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBuffer(&sql,
 						  " AND c.relam = %u "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID); /* Do not expect other AMs here */
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2004,7 +2038,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2025,13 +2059,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2045,12 +2079,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2059,29 +2094,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Toast tables for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
+							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
 							 "FROM toast");
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Indexes for toast relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+							 "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2101,8 +2136,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2112,15 +2148,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2142,10 +2180,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2155,7 +2194,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 58be2c694d..5e8a63a844 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -319,8 +319,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 359abe25a1..8b6326dd3d 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -288,22 +288,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -434,10 +436,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
-- 
2.37.1 (Apple Git-137.1)

From e1b9ab331422d86de466ecd5707249fda6113182 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v26 2/4] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.3--1.4.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 672 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 920 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.3--1.4.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 6d26551fe3..e9e0198276 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 TAP_TESTS = 1
 
diff --git a/contrib/amcheck/amcheck--1.3--1.4.sql b/contrib/amcheck/amcheck--1.3--1.4.sql
new file mode 100644
index 0000000000..5d30784b44
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.3--1.4.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.3--1.4.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.4'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index ab50931f75..e67ace01c9 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.3'
+default_version = '1.4'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..cbc3e27e67
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index cd81cbf3bc..9e7ebc0499 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -24,6 +25,7 @@ install_data(
   'amcheck--1.0--1.1.sql',
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
+  'amcheck--1.3--1.4.sql',
   kwargs: contrib_data_args,
 )
 
@@ -35,6 +37,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..37966423b8
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..f4cc6de8fa
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,672 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int leafdepth;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state);
+static void gist_check_page(GistCheckState *check_state,GistScanItem *stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+							Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the
+	 * downlink we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See
+		 * also gistdoinsert() and gistbulkdelete() handling of such
+		 * tuples. We do consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+						errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the
+		 * parent.
+		 */
+		if (stack->parenttup &&
+			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink
+			 * for current page. It may be missing due to concurrent page
+			 * split, this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for
+			 * both parent and child buffers. Thus parent tuple must
+			 * include keyspace of the child.
+			 */
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+													stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+									(unsigned char *) idxtuple,
+									IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			//Datum old = compatt[i];
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			//pfree(DatumGetPointer(old)); // TODO: this fails. Why?
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* 
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf 
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 2b9c1a9205..40de7c33f5 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -179,6 +179,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.37.1 (Apple Git-137.1)

From 117043bee378170da9ade9a89c2c7979aaf78b79 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v27 1/4] Refactor amcheck to extract common locking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 +++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  31 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 265 ++++++++------------------------
 5 files changed, 273 insertions(+), 198 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d250..97b60c5115 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..bf3427e375
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"), //TODO name AM
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..945f2ad443
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539..1b38e0aba7 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 34990c5cea..2e30c0c693 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,14 +30,13 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -158,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool	parentcheck;
+	bool	heapallindexed;
+	bool	rootdescend;
+	bool	checkunique;
+} BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -240,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -266,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -286,193 +304,44 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
+		bool		has_interval_ops = false;
 
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+				has_interval_ops = true;
+				ereport(ERROR,
 					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel)),
+					has_interval_ops
+					? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+					: 0));
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.42.0

From 2133407a52c5ba94779956715c1b4773415651f8 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v27 4/4] Add GiST support to pg_amcheck

Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 204 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  48 ++++---
 3 files changed, 156 insertions(+), 104 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index a1ad41e766..5cd2a67c23 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,7 +73,7 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
+	 * tables, or similarly if any such pattern applies to indexes, or
 	 * to schemas, then these will be true, otherwise false.  These should
 	 * always agree with what you'd conclude by grep'ing through the exclude
 	 * list.
@@ -98,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -134,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -157,7 +156,8 @@ typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -178,10 +178,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								  PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -195,7 +197,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -322,11 +324,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -381,7 +383,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -649,8 +651,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -783,13 +785,20 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+				prepare_gist_command(&sql, rel, free_slot->connection);
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -867,7 +876,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -913,6 +922,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+						"SELECT %s.gist_index_check("
+						"index := c.oid, heapallindexed := %s)"
+						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+						"WHERE c.oid = %u "
+						"AND c.oid = i.indexrelid "
+						"AND c.relpersistence != 't' "
+						"AND i.indisready AND i.indisvalid AND i.indislive",
+						rel->datinfo->amcheck_schema,
+						(opts.heapallindexed ? "true" : "false"),
+						rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -952,7 +983,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1102,11 +1133,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1115,7 +1146,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1126,7 +1157,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
+			 * We expect the checking functions to return one void row
 			 * each, or zero rows if the check was skipped due to the object
 			 * being in the wrong state to be checked, so we should output
 			 * some sort of warning if we get anything more, not because it
@@ -1141,7 +1172,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1155,7 +1186,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1209,6 +1240,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1422,11 +1455,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1461,14 +1494,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1497,17 +1530,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1765,7 +1798,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1807,7 +1840,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1845,8 +1878,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1869,7 +1902,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1896,7 +1929,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1906,7 +1939,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1914,36 +1947,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1977,12 +2010,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2011,7 +2044,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2019,9 +2052,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2034,15 +2067,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2050,7 +2083,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2071,13 +2104,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2091,12 +2124,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2105,29 +2139,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Toast tables for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
+							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
 							 "FROM toast");
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Indexes for toast relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+							 "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2147,8 +2181,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2158,15 +2193,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2188,10 +2225,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2201,7 +2239,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07..d4cc0664f3 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 4b16bda6a4..7f7bd39f20 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
-- 
2.42.0

From f2b3bd76c511ee3aa85e43aa6e9deac462ff0d4e Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v27 3/4] Add gin_index_parent_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 769 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 1 deletion(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f63252ff33..5c3ea8bc6a 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc7236418..a2bca7c203 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90..5c9ddfe075 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..877ecacb9c
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,769 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb..e1a471474e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.42.0

From c6c84e61c462904b46244a32773d7e2efd0872d7 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v27 2/4] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 672 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 920 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 97b60c5115..f63252ff33 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 0000000000..3fc7236418
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c9..c8ba6d7c9b 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..cbc3e27e67
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba7..15ae94cc90 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..37966423b8
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..3884d0cc25
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,672 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int leafdepth;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState *check_state,GistScanItem *stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+							Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the
+	 * downlink we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See
+		 * also gistdoinsert() and gistbulkdelete() handling of such
+		 * tuples. We do consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+						errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the
+		 * parent.
+		 */
+		if (stack->parenttup &&
+			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink
+			 * for current page. It may be missing due to concurrent page
+			 * split, this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for
+			 * both parent and child buffers. Thus parent tuple must
+			 * include keyspace of the child.
+			 */
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+													stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+									(unsigned char *) idxtuple,
+									IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			//Datum old = compatt[i];
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			//pfree(DatumGetPointer(old)); // TODO: this fails. Why?
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* 
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf 
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615b..6eb526c6bb 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.42.0

From 117043bee378170da9ade9a89c2c7979aaf78b79 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v28 1/4] Refactor amcheck to extract common locking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 +++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  31 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 265 ++++++++------------------------
 5 files changed, 273 insertions(+), 198 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d250..97b60c5115 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 0000000000..bf3427e375
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"), //TODO name AM
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 0000000000..945f2ad443
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539..1b38e0aba7 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 34990c5cea..2e30c0c693 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,14 +30,13 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -158,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool	parentcheck;
+	bool	heapallindexed;
+	bool	rootdescend;
+	bool	checkunique;
+} BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -240,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -266,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -286,193 +304,44 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
+		bool		has_interval_ops = false;
 
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+				has_interval_ops = true;
+				ereport(ERROR,
 					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel)),
+					has_interval_ops
+					? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+					: 0));
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.42.0

From e0dcfd76f22bd609592200525c0045d02052bff6 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v28 4/4] Add GiST support to pg_amcheck

Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 268 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 +++++--
 3 files changed, 210 insertions(+), 131 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index a1ad41e766..8a93fd4140 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,7 +73,7 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
+	 * tables, or similarly if any such pattern applies to indexes, or
 	 * to schemas, then these will be true, otherwise false.  These should
 	 * always agree with what you'd conclude by grep'ing through the exclude
 	 * list.
@@ -98,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -134,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -151,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -178,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								  PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -195,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -287,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -322,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -381,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -530,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -598,36 +606,33 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension. 
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but
+		 * we also support revision just in case. Now it is expected to be
+		 * zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("--checkunique option is not supported by amcheck "
-							   "version \"%s\"", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("--checkunique option is not supported by amcheck "
+							"version \"%s\"", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -649,8 +654,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -783,13 +788,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -867,7 +888,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -913,6 +934,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+						"SELECT %s.gist_index_check("
+						"index := c.oid, heapallindexed := %s)"
+						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+						"WHERE c.oid = %u "
+						"AND c.oid = i.indexrelid "
+						"AND c.relpersistence != 't' "
+						"AND i.indisready AND i.indisvalid AND i.indislive",
+						rel->datinfo->amcheck_schema,
+						(opts.heapallindexed ? "true" : "false"),
+						rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -952,7 +995,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1102,11 +1145,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1115,7 +1158,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1126,7 +1169,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
+			 * We expect the checking functions to return one void row
 			 * each, or zero rows if the check was skipped due to the object
 			 * being in the wrong state to be checked, so we should output
 			 * some sort of warning if we get anything more, not because it
@@ -1141,7 +1184,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1155,7 +1198,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1209,6 +1252,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1422,11 +1467,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1461,14 +1506,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1497,17 +1542,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1765,7 +1810,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1807,7 +1852,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1845,8 +1890,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1869,7 +1914,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1896,7 +1941,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1906,7 +1951,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1914,36 +1959,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1977,12 +2022,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2011,7 +2056,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2019,9 +2064,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2034,15 +2079,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2050,7 +2095,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2071,13 +2116,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2091,12 +2136,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2105,29 +2151,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Toast tables for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
+							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
 							 "FROM toast");
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Indexes for toast relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+							 "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2147,8 +2193,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2158,15 +2205,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2188,10 +2237,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2201,7 +2251,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07..d4cc0664f3 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 4b16bda6a4..7da498ea98 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: --checkunique option is not supported by amcheck version "1.3"/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.42.0

From f2b3bd76c511ee3aa85e43aa6e9deac462ff0d4e Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v28 3/4] Add gin_index_parent_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 769 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 1 deletion(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f63252ff33..5c3ea8bc6a 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc7236418..a2bca7c203 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 0000000000..43fd769a50
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90..5c9ddfe075 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 0000000000..9771afffa5
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 0000000000..877ecacb9c
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,769 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb..e1a471474e 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.42.0

From c6c84e61c462904b46244a32773d7e2efd0872d7 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v28 2/4] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 672 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 920 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 97b60c5115..f63252ff33 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 0000000000..3fc7236418
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c9..c8ba6d7c9b 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 0000000000..cbc3e27e67
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba7..15ae94cc90 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 0000000000..37966423b8
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 0000000000..3884d0cc25
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,672 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int leafdepth;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState *check_state,GistScanItem *stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+							Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the
+	 * downlink we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See
+		 * also gistdoinsert() and gistbulkdelete() handling of such
+		 * tuples. We do consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+						errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the
+		 * parent.
+		 */
+		if (stack->parenttup &&
+			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink
+			 * for current page. It may be missing due to concurrent page
+			 * split, this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for
+			 * both parent and child buffers. Thus parent tuple must
+			 * include keyspace of the child.
+			 */
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+													stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+									(unsigned char *) idxtuple,
+									IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			//Datum old = compatt[i];
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			//pfree(DatumGetPointer(old)); // TODO: this fails. Why?
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* 
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf 
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615b..6eb526c6bb 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.42.0

From 7377e8d1d0073da6144c86090af56fea46d74253 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v28-review 01/13] Refactor amcheck to extract common locking
 routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Other indexes will need to do same precautions before doing checks:
 - ensuring index is checkable
 - switching user context
 - taking care about GUCs changed by index functions
To reuse existing functionality this commit moves it to amcheck.c.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile        |   1 +
 contrib/amcheck/amcheck.c       | 173 +++++++++++++++++++++
 contrib/amcheck/amcheck.h       |  31 ++++
 contrib/amcheck/meson.build     |   1 +
 contrib/amcheck/verify_nbtree.c | 265 ++++++++------------------------
 5 files changed, 273 insertions(+), 198 deletions(-)
 create mode 100644 contrib/amcheck/amcheck.c
 create mode 100644 contrib/amcheck/amcheck.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..97b60c5115a 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	amcheck.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
new file mode 100644
index 00000000000..bf3427e375d
--- /dev/null
+++ b/contrib/amcheck/amcheck.c
@@ -0,0 +1,173 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Relation suitable for checking */
+	index_checkable(indrel, am_id);
+
+	if (amcheck_index_mainfork_expected(indrel))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+void
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("only B-Tree indexes are supported as targets for verification"), //TODO name AM
+				 errdetail("Relation \"%s\" is not a B-Tree index.",
+						   RelationGetRelationName(rel))));
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+}
diff --git a/contrib/amcheck/amcheck.h b/contrib/amcheck/amcheck.h
new file mode 100644
index 00000000000..945f2ad4437
--- /dev/null
+++ b/contrib/amcheck/amcheck.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern void index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..1b38e0aba77 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 34990c5cea3..2e30c0c693e 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,14 +30,13 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "amcheck.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
 #include "commands/tablecmds.h"
 #include "common/pg_prng.h"
 #include "lib/bloomfilter.h"
-#include "miscadmin.h"
-#include "storage/lmgr.h"
 #include "storage/smgr.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
@@ -158,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool	parentcheck;
+	bool	heapallindexed;
+	bool	rootdescend;
+	bool	checkunique;
+} BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -240,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -266,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -286,193 +304,44 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
-
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
+		bool		has_interval_ops = false;
 
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+				has_interval_ops = true;
+				ereport(ERROR,
 					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+						RelationGetRelationName(indrel)),
+					has_interval_ops
+					? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+					: 0));
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.45.2

From 60a10f1609820462259eadd83e822e9709d038e6 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:09:45 +0200
Subject: [PATCH v28-review 02/13] review

---
 contrib/amcheck/amcheck.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index bf3427e375d..41cdb5e35a4 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -8,6 +8,8 @@
  * IDENTIFICATION
  *	  contrib/amcheck/amcheck.c
  *
+ *
+ * XXX I'd probably call this verify_common.c or something like that.
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
@@ -29,6 +31,8 @@ static bool amcheck_index_mainfork_expected(Relation rel);
  * where there is simply nothing to verify.
  *
  * NB: Caller should call index_checkable() before calling here.
+ *
+ * XXX Wouldn't it be more natural to have this check in index_checkable?
  */
 static bool
 amcheck_index_mainfork_expected(Relation rel)
@@ -45,6 +49,9 @@ amcheck_index_mainfork_expected(Relation rel)
 	return false;
 }
 
+/*
+ * XXX missing comment, and it's the longest/most important function in the file
+ */
 void
 amcheck_lock_relation_and_check(Oid indrelid,
 								Oid am_id,
@@ -153,7 +160,7 @@ index_checkable(Relation rel, Oid am_id)
 		rel->rd_rel->relam != am_id)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"), //TODO name AM
+				 errmsg("only B-Tree indexes are supported as targets for verification"), //FIXME name AM, shouldn't be hhard to lookup in AMOID syscache
 				 errdetail("Relation \"%s\" is not a B-Tree index.",
 						   RelationGetRelationName(rel))));
 
-- 
2.45.2

From f82459e7c4b082b91707ed9fb4252fc8d72fa058 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:45:49 +0200
Subject: [PATCH v28-review 03/13] pgindent

---
 contrib/amcheck/amcheck.c       |  3 ++-
 contrib/amcheck/verify_nbtree.c | 22 +++++++++++-----------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/contrib/amcheck/amcheck.c b/contrib/amcheck/amcheck.c
index 41cdb5e35a4..964c06e7376 100644
--- a/contrib/amcheck/amcheck.c
+++ b/contrib/amcheck/amcheck.c
@@ -158,9 +158,10 @@ index_checkable(Relation rel, Oid am_id)
 {
 	if (rel->rd_rel->relkind != RELKIND_INDEX ||
 		rel->rd_rel->relam != am_id)
+		/* FIXME name AM, shouldn't be hhard to lookup in AMOID syscache */
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"), //FIXME name AM, shouldn't be hhard to lookup in AMOID syscache
+				 errmsg("only B-Tree indexes are supported as targets for verification"),
 				 errdetail("Relation \"%s\" is not a B-Tree index.",
 						   RelationGetRelationName(rel))));
 
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 2e30c0c693e..b630e36ead7 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -162,11 +162,11 @@ typedef struct BtreeLastVisibleEntry
  */
 typedef struct BTCallbackState
 {
-	bool	parentcheck;
-	bool	heapallindexed;
-	bool	rootdescend;
-	bool	checkunique;
-} BTCallbackState;
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
 
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
@@ -330,13 +330,13 @@ bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool rea
 		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
 			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
 				has_interval_ops = true;
-				ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
 						RelationGetRelationName(indrel)),
-					has_interval_ops
-					? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					: 0));
+				 has_interval_ops
+				 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+				 : 0));
 	}
 
 	/* Check index, possibly against table it is an index on */
-- 
2.45.2

From 7b33c5ac16672d1894a81bda110330b830b3fa2c Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v28-review 04/13] Add gist_index_check() function to verify
 GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 672 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 920 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 97b60c5115a..f63252ff33c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba77..15ae94cc90f 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..3884d0cc25b
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,672 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "amcheck.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of referenced page.
+	 * This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page.
+	 * It's necessary to avoid missing some subtrees from page, that was
+	 * split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrapencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+} GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+	/* Debug counter */
+	int64		heaptuplespresent;
+	/* GiST state */
+	GISTSTATE  *state;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int leafdepth;
+} GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState *check_state,GistScanItem *stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+static void
+gist_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check. Allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		gist_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot,	/* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+							Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the
+	 * downlink we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See
+		 * also gistdoinsert() and gistbulkdelete() handling of such
+		 * tuples. We do consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+						errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+						errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the
+		 * parent.
+		 */
+		if (stack->parenttup &&
+			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink
+			 * for current page. It may be missing due to concurrent page
+			 * split, this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for
+			 * both parent and child buffers. Thus parent tuple must
+			 * include keyspace of the child.
+			 */
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+													stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+						stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+									(unsigned char *) idxtuple,
+									IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+			  Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			//Datum old = compatt[i];
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			//pfree(DatumGetPointer(old)); // TODO: this fails. Why?
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/* 
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf 
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular moment
+			 * tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
+	 * and gist never uses either.  Verify that line pointer has storage, too,
+	 * since even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.45.2

From b6a67accbe69af78597b65f9b41560af00e10078 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:38:13 +0200
Subject: [PATCH v28-review 05/13] review

---
 contrib/amcheck/verify_gist.c | 40 +++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
index 3884d0cc25b..5ea3e216b7d 100644
--- a/contrib/amcheck/verify_gist.c
+++ b/contrib/amcheck/verify_gist.c
@@ -54,7 +54,7 @@ typedef struct GistScanItem
 
 	/*
 	 * Reference to parent page for re-locking in case of found parent-child
-	 * tuple discrapencies.
+	 * tuple discrepencies.
 	 */
 	BlockNumber parentblk;
 
@@ -66,8 +66,11 @@ typedef struct GistCheckState
 {
 	/* Bloom filter fingerprints index tuples */
 	bloom_filter *filter;
-	/* Debug counter */
+
+	/* Debug counter	FIXME what does 'debug counter' mean?*/
 	int64		heaptuplespresent;
+
+	/* XXX nitpick: I'd move these 'generic' fields to the beginning */
 	/* GiST state */
 	GISTSTATE  *state;
 
@@ -106,8 +109,7 @@ static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
 
 /*
  * gist_index_check(index regclass)
- *
- * Verify integrity of GiST index.
+ *		Verify integrity of GiST index.
  *
  * Acquires AccessShareLock on heap & index relations.
  */
@@ -126,6 +128,10 @@ gist_index_check(PG_FUNCTION_ARGS)
 	PG_RETURN_VOID();
 }
 
+/*
+ * XXX This talks about 'heapallindexed' but it initializes a snapshot too,
+ * but isn't that unrelated / confusing?
+ */
 static void
 gist_init_heapallindexed(Relation rel, GistCheckState * result)
 {
@@ -145,7 +151,6 @@ gist_init_heapallindexed(Relation rel, GistCheckState * result)
 
 	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
 
-
 	/*
 	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
 	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
@@ -171,7 +176,11 @@ gist_init_heapallindexed(Relation rel, GistCheckState * result)
  * Main entry point for GiST check. Allocates memory context and scans through
  * GiST graph. This scan is performed in a depth-first search using a stack of
  * GistScanItem-s. Initially this stack contains only root block number. On
- * each iteration top block numbmer is replcaed by referenced block numbers.
+ * each iteration the top block number is replaced by referenced block numbers.
+ *
+ * XXX I'd move the following paragraph right before "allocates memory". It
+ * describes what the function does, while the "allocates memory" is more
+ * a description of "how" it is done.
  *
  * This function verifies that tuples of internal pages cover all
  * the key space of each tuple on leaf page.  To do this we invoke
@@ -356,10 +365,12 @@ gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
 	pfree(check_state);
 }
 
-static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
-							Page page, bool heapallindexed, BufferAccessStrategy strategy)
+static void
+gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
 {
 	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
 	/* Check that the tree has the same height in all branches */
 	if (GistPageIsLeaf(page))
 	{
@@ -468,7 +479,7 @@ static void gist_check_page(GistCheckState *check_state, GistScanItem *stack,
  */
 static IndexTuple
 gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
-			  Datum *attdata, bool *isnull, ItemPointerData tid)
+						Datum *attdata, bool *isnull, ItemPointerData tid)
 {
 	Datum		compatt[INDEX_MAX_KEYS];
 	IndexTuple	res;
@@ -525,6 +536,7 @@ gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
 	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
 
 	itup->t_tid = *tid;
+
 	/* Probe Bloom filter -- tuple should be present */
 	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
 							IndexTupleSize(itup)))
@@ -602,9 +614,9 @@ gist_refind_parent(Relation rel,
 
 	if (GistPageIsLeaf(parentpage))
 	{
-		/* 
+		/*
 		 * Currently GiST never deletes internal pages, thus they can never
-		 * become leaf 
+		 * become leaf.
 		 */
 		ereport(ERROR,
 				(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -635,6 +647,10 @@ gist_refind_parent(Relation rel,
 	return result;
 }
 
+/*
+ * XXX What does this do? Maybe it should be in core or some common file?
+ * Seems to be used in verify_btree.c too.
+ */
 static ItemId
 PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
 					 OffsetNumber offset)
@@ -656,6 +672,8 @@ PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
 	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since nbtree
 	 * and gist never uses either.  Verify that line pointer has storage, too,
 	 * since even LP_DEAD items should.
+	 *
+	 * XXX why does this reference nbtree?
 	 */
 	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
 		ItemIdGetLength(itemid) == 0)
-- 
2.45.2

From 69c374628c6b1fc7b90703b381ac3e63f9b64dff Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:56:41 +0200
Subject: [PATCH v28-review 06/13] pgindent

---
 contrib/amcheck/verify_gist.c | 86 +++++++++++++++++------------------
 1 file changed, 43 insertions(+), 43 deletions(-)

diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
index 5ea3e216b7d..63f6175e17c 100644
--- a/contrib/amcheck/verify_gist.c
+++ b/contrib/amcheck/verify_gist.c
@@ -40,15 +40,14 @@ typedef struct GistScanItem
 	BlockNumber blkno;
 
 	/*
-	 * Correctess of this parent tuple will be checked against contents of referenced page.
-	 * This tuple will be NULL for root block.
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
 	 */
 	IndexTuple	parenttup;
 
 	/*
-	 * LSN to hande concurrent scan of the page.
-	 * It's necessary to avoid missing some subtrees from page, that was
-	 * split just before we read it.
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
 	 */
 	XLogRecPtr	parentlsn;
 
@@ -60,14 +59,14 @@ typedef struct GistScanItem
 
 	/* Pointer to a next stack item. */
 	struct GistScanItem *next;
-} GistScanItem;
+}			GistScanItem;
 
 typedef struct GistCheckState
 {
 	/* Bloom filter fingerprints index tuples */
 	bloom_filter *filter;
 
-	/* Debug counter	FIXME what does 'debug counter' mean?*/
+	/* Debug counter	FIXME what does 'debug counter' mean? */
 	int64		heaptuplespresent;
 
 	/* XXX nitpick: I'd move these 'generic' fields to the beginning */
@@ -84,15 +83,15 @@ typedef struct GistCheckState
 	BlockNumber scannedblocks;
 	BlockNumber deltablocks;
 
-	int leafdepth;
-} GistCheckState;
+	int			leafdepth;
+}			GistCheckState;
 
 PG_FUNCTION_INFO_V1(gist_index_check);
 
 static void gist_init_heapallindexed(Relation rel, GistCheckState * result);
 static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
 											   void *callback_state, bool readonly);
-static void gist_check_page(GistCheckState *check_state,GistScanItem *stack,
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
 							Page page, bool heapallindexed,
 							BufferAccessStrategy strategy);
 static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
@@ -105,7 +104,7 @@ static void gist_tuple_present_callback(Relation index, ItemPointer tid,
 										Datum *values, bool *isnull,
 										bool tupleIsAlive, void *checkstate);
 static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
-			  Datum *attdata, bool *isnull, ItemPointerData tid);
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
 
 /*
  * gist_index_check(index regclass)
@@ -292,6 +291,7 @@ gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
 		if (!GistPageIsLeaf(page))
 		{
 			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
 			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
 			{
 				/* Internal page, so recurse to the child */
@@ -327,7 +327,7 @@ gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
 		TableScanDesc scan;
 
 		scan = table_beginscan_strat(heaprel,	/* relation */
-									 check_state->snapshot,	/* snapshot */
+									 check_state->snapshot, /* snapshot */
 									 0, /* number of keys */
 									 NULL,	/* scan key */
 									 true,	/* buffer access strategy OK */
@@ -366,7 +366,7 @@ gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
 }
 
 static void
-gist_check_page(GistCheckState *check_state, GistScanItem *stack,
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
 				Page page, bool heapallindexed, BufferAccessStrategy strategy)
 {
 	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
@@ -379,13 +379,13 @@ gist_check_page(GistCheckState *check_state, GistScanItem *stack,
 		else if (stack->depth != check_state->leafdepth)
 			ereport(ERROR,
 					(errcode(ERRCODE_INDEX_CORRUPTED),
-						errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
 							RelationGetRelationName(check_state->rel), stack->blkno)));
 	}
 
 	/*
-	 * Check that each tuple looks valid, and is consistent with the
-	 * downlink we followed when we stepped on this page.
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
 	 */
 	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
 	{
@@ -393,27 +393,26 @@ gist_check_page(GistCheckState *check_state, GistScanItem *stack,
 		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
 
 		/*
-		 * Check that it's not a leftover invalid tuple from pre-9.1 See
-		 * also gistdoinsert() and gistbulkdelete() handling of such
-		 * tuples. We do consider it error here.
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
 		 */
 		if (GistTupleIsInvalid(idxtuple))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-						errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
 							RelationGetRelationName(check_state->rel), stack->blkno, i),
-						errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
-						errhint("Please REINDEX it.")));
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
 
 		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
 			ereport(ERROR,
 					(errcode(ERRCODE_INDEX_CORRUPTED),
-						errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
 							RelationGetRelationName(check_state->rel), stack->blkno, i)));
 
 		/*
-		 * Check if this tuple is consistent with the downlink in the
-		 * parent.
+		 * Check if this tuple is consistent with the downlink in the parent.
 		 */
 		if (stack->parenttup &&
 			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
@@ -421,26 +420,26 @@ gist_check_page(GistCheckState *check_state, GistScanItem *stack,
 			/*
 			 * There was a discrepancy between parent and child tuples. We
 			 * need to verify it is not a result of concurrent call of
-			 * gistplacetopage(). So, lock parent and try to find downlink
-			 * for current page. It may be missing due to concurrent page
-			 * split, this is OK.
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
 			 *
-			 * Note that when we aquire parent tuple now we hold lock for
-			 * both parent and child buffers. Thus parent tuple must
-			 * include keyspace of the child.
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
 			 */
 			pfree(stack->parenttup);
 			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
-													stack->blkno, strategy);
+												  stack->blkno, strategy);
 
 			/* We found it - make a final check before failing */
 			if (!stack->parenttup)
 				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
-						stack->blkno, stack->parentblk);
+					 stack->blkno, stack->parentblk);
 			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
 				ereport(ERROR,
 						(errcode(ERRCODE_INDEX_CORRUPTED),
-							errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
 								RelationGetRelationName(check_state->rel), stack->blkno, i)));
 			else
 			{
@@ -454,16 +453,17 @@ gist_check_page(GistCheckState *check_state, GistScanItem *stack,
 		{
 			if (heapallindexed)
 				bloom_add_element(check_state->filter,
-									(unsigned char *) idxtuple,
-									IndexTupleSize(idxtuple));
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
 		}
 		else
 		{
 			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
 			if (off != 0xffff)
 				ereport(ERROR,
 						(errcode(ERRCODE_INDEX_CORRUPTED),
-							errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
 								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
 		}
 	}
@@ -503,18 +503,18 @@ gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
 							RelationGetRelationName(r))));
 		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
 		{
-			//Datum old = compatt[i];
+			/* Datum old = compatt[i]; */
 			/* Key attributes must never be compressed */
 			if (i < IndexRelationGetNumberOfKeyAttributes(r))
 				ereport(ERROR,
 						(errcode(ERRCODE_INDEX_CORRUPTED),
-							errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
 								ItemPointerGetBlockNumber(&tid),
 								ItemPointerGetOffsetNumber(&tid),
 								RelationGetRelationName(r))));
 
 			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
-			//pfree(DatumGetPointer(old)); // TODO: this fails. Why?
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
 		}
 	}
 
@@ -620,7 +620,7 @@ gist_refind_parent(Relation rel,
 		 */
 		ereport(ERROR,
 				(errcode(ERRCODE_INDEX_CORRUPTED),
-					errmsg("index \"%s\" internal page %d became leaf",
+				 errmsg("index \"%s\" internal page %d became leaf",
 						RelationGetRelationName(rel), parentblkno)));
 	}
 
@@ -634,8 +634,8 @@ gist_refind_parent(Relation rel,
 		{
 			/*
 			 * Found it! Make copy and return it while both parent and child
-			 * pages are locked. This guaranties that at this particular moment
-			 * tuples must be coherent to each other.
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
 			 */
 			result = CopyIndexTuple(itup);
 			break;
-- 
2.45.2

From 60aa76aaea5e21a6821aa2be44f11bf35f7ef94b Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v28-review 07/13] Add gin_index_parent_check() to verify GIN
 index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 769 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 7 files changed, 905 insertions(+), 1 deletion(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index f63252ff33c..5c3ea8bc6a4 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	amcheck.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..a2bca7c2037 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_parent_check()
+--
+CREATE FUNCTION gin_index_parent_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_parent_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_parent_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..43fd769a506
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_parent_check('gin_check_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+ gin_index_parent_check 
+------------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90f..5c9ddfe0758 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..9771afffa5c
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_parent_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_parent_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..877ecacb9c1
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,769 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "amcheck.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_parent_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_parent_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_parent_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum parent_key = gintuple_get_key(&state,
+												stack->parenttup,
+												&parent_key_category);
+			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
+											  page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum parent_key = gintuple_get_key(&state,
+													stack->parenttup,
+													&parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..e1a471474e6 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_parent_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_parent_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_parent_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
-- 
2.45.2

From 7ed4f7a82663d576bdb928a2767920fff36d60f9 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:40:22 +0200
Subject: [PATCH v28-review 08/13] review

---
 contrib/amcheck/amcheck--1.4--1.5.sql | 2 +-
 contrib/amcheck/verify_gin.c          | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index a2bca7c2037..7414b611e06 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -14,7 +14,7 @@ LANGUAGE C STRICT;
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
 
 -- gin_index_parent_check()
---
+-- XXX why is this not called simply gin_index_check?
 CREATE FUNCTION gin_index_parent_check(index regclass)
 RETURNS VOID
 AS 'MODULE_PATHNAME', 'gin_index_parent_check'
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 877ecacb9c1..2a63ba6b83e 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -732,6 +732,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 	return result;
 }
 
+/* XXX yet another copy of this? */
 static ItemId
 PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
 					 OffsetNumber offset)
-- 
2.45.2

From d280ad00e2834093b838c1cdf0dd8539920b2724 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:47:45 +0200
Subject: [PATCH v28-review 09/13] pgindent

---
 contrib/amcheck/verify_gin.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 2a63ba6b83e..8ce112fe49e 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -38,7 +38,7 @@ typedef struct GinScanItem
 	XLogRecPtr	parentlsn;
 	BlockNumber blkno;
 	struct GinScanItem *next;
-} GinScanItem;
+}			GinScanItem;
 
 /*
  * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
@@ -50,7 +50,7 @@ typedef struct GinPostingTreeScanItem
 	BlockNumber parentblk;
 	BlockNumber blkno;
 	struct GinPostingTreeScanItem *next;
-} GinPostingTreeScanItem;
+}			GinPostingTreeScanItem;
 
 
 PG_FUNCTION_INFO_V1(gin_index_parent_check);
@@ -434,11 +434,11 @@ gin_check_parent_keys_consistency(Relation rel,
 		if (stack->parenttup != NULL)
 		{
 			GinNullCategory parent_key_category;
-			Datum parent_key = gintuple_get_key(&state,
-												stack->parenttup,
-												&parent_key_category);
-			ItemId iid = PageGetItemIdCareful(rel, stack->blkno,
-											  page, maxoff);
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
 			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
@@ -521,9 +521,9 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
-				Datum parent_key = gintuple_get_key(&state,
-													stack->parenttup,
-													&parent_key_category);
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
 
 				if (ginCompareEntries(&state, attnum, current_key,
 									  current_key_category, parent_key,
-- 
2.45.2

From 905964ef70d1955fe7270c6b9d02c73c1c6dbb5f Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v28-review 10/13] Add GiST support to pg_amcheck

Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 268 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 +++++--
 3 files changed, 210 insertions(+), 131 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index a1ad41e7664..8a93fd4140d 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,7 +73,7 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
+	 * tables, or similarly if any such pattern applies to indexes, or
 	 * to schemas, then these will be true, otherwise false.  These should
 	 * always agree with what you'd conclude by grep'ing through the exclude
 	 * list.
@@ -98,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -134,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -151,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -178,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								  PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -195,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -287,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -322,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -381,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -530,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -598,36 +606,33 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension. 
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but
+		 * we also support revision just in case. Now it is expected to be
+		 * zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("--checkunique option is not supported by amcheck "
-							   "version \"%s\"", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("--checkunique option is not supported by amcheck "
+							"version \"%s\"", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -649,8 +654,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -783,13 +788,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -867,7 +888,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -913,6 +934,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+						"SELECT %s.gist_index_check("
+						"index := c.oid, heapallindexed := %s)"
+						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+						"WHERE c.oid = %u "
+						"AND c.oid = i.indexrelid "
+						"AND c.relpersistence != 't' "
+						"AND i.indisready AND i.indisvalid AND i.indislive",
+						rel->datinfo->amcheck_schema,
+						(opts.heapallindexed ? "true" : "false"),
+						rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -952,7 +995,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1102,11 +1145,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1115,7 +1158,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1126,7 +1169,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
+			 * We expect the checking functions to return one void row
 			 * each, or zero rows if the check was skipped due to the object
 			 * being in the wrong state to be checked, so we should output
 			 * some sort of warning if we get anything more, not because it
@@ -1141,7 +1184,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1155,7 +1198,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1209,6 +1252,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1422,11 +1467,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1461,14 +1506,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1497,17 +1542,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1765,7 +1810,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1807,7 +1852,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1845,8 +1890,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1869,7 +1914,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1896,7 +1941,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1906,7 +1951,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1914,36 +1959,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1977,12 +2022,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2011,7 +2056,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2019,9 +2064,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2034,15 +2079,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2050,7 +2095,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2071,13 +2116,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2091,12 +2136,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2105,29 +2151,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Toast tables for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
+							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
 							 "FROM toast");
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
 							 " UNION"
 		/* Indexes for toast relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+							 "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2147,8 +2193,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2158,15 +2205,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2188,10 +2237,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2201,7 +2251,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 4b16bda6a48..7da498ea98d 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: --checkunique option is not supported by amcheck version "1.3"/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.45.2

From 67b59501fe46ecc4899324f6019d0d7a213d57ab Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 15:58:38 +0200
Subject: [PATCH v28-review 11/13] review

---
 src/bin/pg_amcheck/pg_amcheck.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 8a93fd4140d..101cf4f0ae7 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -606,7 +606,7 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. 
+		 * Check the version of amcheck extension.
 		 */
 		amcheck_version = PQgetvalue(result, 0, 1);
 
-- 
2.45.2

From 62f23870f276e72ed78e1700f550788bea443832 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 16:00:55 +0200
Subject: [PATCH v28-review 12/13] pgindent

---
 src/bin/pg_amcheck/pg_amcheck.c | 64 ++++++++++++++++-----------------
 1 file changed, 31 insertions(+), 33 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 101cf4f0ae7..62f43708da9 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -73,10 +73,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -180,7 +179,7 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
 static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
-								  PGconn *conn);
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
@@ -611,9 +610,8 @@ main(int argc, char *argv[])
 		amcheck_version = PQgetvalue(result, 0, 1);
 
 		/*
-		 * Now amcheck has only major and minor versions in the string but
-		 * we also support revision just in case. Now it is expected to be
-		 * zero.
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
 		 */
 		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
@@ -625,7 +623,7 @@ main(int argc, char *argv[])
 		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
 		{
 			pg_log_warning("--checkunique option is not supported by amcheck "
-							"version \"%s\"", amcheck_version);
+						   "version \"%s\"", amcheck_version);
 			dat->is_checkunique = false;
 		}
 		else
@@ -944,16 +942,16 @@ prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 	resetPQExpBuffer(sql);
 
 	appendPQExpBuffer(sql,
-						"SELECT %s.gist_index_check("
-						"index := c.oid, heapallindexed := %s)"
-						"\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
-						"WHERE c.oid = %u "
-						"AND c.oid = i.indexrelid "
-						"AND c.relpersistence != 't' "
-						"AND i.indisready AND i.indisvalid AND i.indislive",
-						rel->datinfo->amcheck_schema,
-						(opts.heapallindexed ? "true" : "false"),
-						rel->reloid);
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
 }
 
 /*
@@ -1169,12 +1167,12 @@ verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -2155,11 +2153,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
 		appendPQExpBuffer(&sql,
-							 " UNION"
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
-							 "FROM toast");
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
 	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
@@ -2169,11 +2167,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 							 "FROM index");
 	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 		appendPQExpBuffer(&sql,
-							 " UNION"
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
-							 "FROM toast_index", BTREE_AM_OID);
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
-- 
2.45.2

From 5fcd217ab30665df8b3c3a914375ff6dee1b7b60 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tv@fuzzy.cz>
Date: Wed, 10 Jul 2024 17:33:28 +0200
Subject: [PATCH v28-review 13/13] assert in GIN debug message

---
 contrib/amcheck/verify_gin.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 8ce112fe49e..c9c20bcb3af 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -293,11 +293,14 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			{
 				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
 
+/*
+ * triggers assert in ItemPointerGetOffsetNumber
+ *
 				elog(DEBUG3, "key (%u, %u) -> %u",
 					 ItemPointerGetBlockNumber(&posting_item->key),
 					 ItemPointerGetOffsetNumber(&posting_item->key),
 					 BlockIdGetBlockNumber(&posting_item->child_blkno));
-
+*/
 				if (i == maxoff &&
 					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
 				{
-- 
2.45.2

From 31fbef4e654946f3513b81ddf437cabf41ae3e74 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Fri, 18 Oct 2024 12:39:48 +0000
Subject: [PATCH v28] Fix memory leak in `gist_check_page`

---
 contrib/amcheck/verify_gist.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
index 63f6175e17c..3241f84cba7 100644
--- a/contrib/amcheck/verify_gist.c
+++ b/contrib/amcheck/verify_gist.c
@@ -391,6 +391,7 @@ gist_check_page(GistCheckState * check_state, GistScanItem * stack,
 	{
 		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
 		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
 
 		/*
 		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
@@ -414,8 +415,10 @@ gist_check_page(GistCheckState * check_state, GistScanItem * stack,
 		/*
 		 * Check if this tuple is consistent with the downlink in the parent.
 		 */
-		if (stack->parenttup &&
-			gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
 		{
 			/*
 			 * There was a discrepancy between parent and child tuples. We
@@ -428,6 +431,8 @@ gist_check_page(GistCheckState * check_state, GistScanItem * stack,
 			 * parent and child buffers. Thus parent tuple must include
 			 * keyspace of the child.
 			 */
+
+			pfree(tmpTuple);
 			pfree(stack->parenttup);
 			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
 												  stack->blkno, strategy);
-- 
2.34.1

From b099ffb366e0f4e08a08a5cdefe971203f7232de Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v29 4/5] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 769 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 src/tools/pgindent/pgindent            |   2 +-
 8 files changed, 906 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 952e458c53b..c01f8e618f3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..c013abc4f55 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90f..5c9ddfe0758 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..47b6e81fbc4
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,769 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+		{
+			ipd = palloc(0);
+		}
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			}
+			else
+			{
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+			}
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+			{
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+			}
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+						else
+						{
+							/*
+							 * But now it is properly adjusted - nothing to do
+							 * here.
+							 */
+						}
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+				{
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				}
+				else
+				{
+					ptr->parenttup = NULL;
+				}
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..55f2b587e57 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
diff --git a/src/tools/pgindent/pgindent b/src/tools/pgindent/pgindent
index e889af6b1e4..e5ac0410665 100755
--- a/src/tools/pgindent/pgindent
+++ b/src/tools/pgindent/pgindent
@@ -13,7 +13,7 @@ use IO::Handle;
 use Getopt::Long;
 
 # Update for pg_bsd_indent version
-my $INDENT_VERSION = "2.1.2";
+my $INDENT_VERSION = "2.1.1";
 
 # Our standard indent settings
 my $indent_opts =
-- 
2.34.1

From 77b128cb0b0c10cf71d3282cd1d55c473b691a7d Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v29 1/5] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 8b82797c10f..746f7ce09fb 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.34.1

From db939f443a47120c7c1adc8d7b47c5f0025b2224 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v29 5/5] Add GiST support to pg_amcheck

Proof of concept patch for pg_amcheck binary support
for GIST & GIN index checks.

Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 292 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 ++++--
 3 files changed, 221 insertions(+), 144 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 0c05cf58bce..cf01a370b1b 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -39,8 +39,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -74,10 +73,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -98,14 +96,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -134,7 +132,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -151,13 +149,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -178,10 +178,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -195,7 +197,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -287,6 +289,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -322,11 +325,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -381,7 +384,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -530,6 +533,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -598,36 +605,32 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension.
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("option %s is not supported by amcheck version %s",
-							   "--checkunique", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("option %s is not supported by amcheck version %s",
+						   "--checkunique", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -649,8 +652,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -783,13 +786,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -867,7 +886,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -913,6 +932,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -952,7 +993,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1102,11 +1143,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1115,7 +1156,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1126,12 +1167,12 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -1141,7 +1182,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1155,7 +1196,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1209,6 +1250,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1422,11 +1465,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1461,14 +1504,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1497,17 +1540,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1765,7 +1808,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1807,7 +1850,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1845,8 +1888,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1869,7 +1912,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1896,7 +1939,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1906,7 +1949,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1914,36 +1957,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1977,12 +2020,12 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ('r', 'S', 'm', 't', 'i') "
 						  "AND ((c.relam = %u AND c.relkind IN ('r', 'S', 'm', 't')) OR "
-						  "(c.relam = %u AND c.relkind = 'i'))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = 'i'))",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2011,7 +2054,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2019,9 +2062,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2034,15 +2077,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = 'i'",
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2050,7 +2093,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2071,13 +2114,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u"
+						  " AND c.relam = %u "
 						  " AND c.relkind = 'i')",
 						  BTREE_AM_OID);
 	}
@@ -2091,12 +2134,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2105,29 +2149,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast");
-	if (!opts.no_btree_expansion)
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2147,8 +2191,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2158,15 +2203,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2188,10 +2235,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2201,7 +2249,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 2b57c4dbac1..0aa66b24258 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: option --checkunique is not supported by amcheck version 1.3/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.34.1

From 94f71608c8ab98ee6218cc497af55c28bc7b9abf Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v29 3/5] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 687 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 935 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..952e458c53b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba77..15ae94cc90f 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..477150ac802
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,687 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "verify_common.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrepencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+}			GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* GiST state */
+	GISTSTATE  *state;
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* Debug counter for reporting percentage of work already done */
+	int64		heaptuplespresent;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int			leafdepth;
+}			GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void giststate_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+* Initaliaze GIST state filed needed to perform.
+* This initialized bloom filter and snapshot.
+*/
+static void
+giststate_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * This check allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		giststate_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot, /* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the parent.
+		 */
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
+			 */
+
+			pfree(tmpTuple);
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+												  stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+					 stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+						Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			/* Datum old = compatt[i]; */
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/*
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.34.1

From c945a914331f4d558eae15ecc7d17ba2c847d2eb Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v29 2/5] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..1b38e0aba77 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..acdcf5729f7
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 746f7ce09fb..e338891671a 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.34.1

From e78bc24a3a355c5731cb677b89456ceb9fbd9b55 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v30 1/5] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index ffe4f721672..c76349bf436 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.34.1

From 5cb507ead70de64cd966821045a77ae25ef2433a Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v30 2/5] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..1b38e0aba77 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..acdcf5729f7
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index c76349bf436..1da4f0c3461 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.34.1

From 1cd7e7650d1723c11ffc001e8ee8376f61884c60 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v30 4/5] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 755 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 src/tools/pgindent/pgindent            |   2 +-
 8 files changed, 892 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 952e458c53b..c01f8e618f3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..c013abc4f55 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90f..5c9ddfe0758 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..39baae40f0c
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,755 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						* Check if it is properly adjusted.
+						* If succeed, procced to the next key.
+						*/
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..55f2b587e57 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
diff --git a/src/tools/pgindent/pgindent b/src/tools/pgindent/pgindent
index e889af6b1e4..e5ac0410665 100755
--- a/src/tools/pgindent/pgindent
+++ b/src/tools/pgindent/pgindent
@@ -13,7 +13,7 @@ use IO::Handle;
 use Getopt::Long;
 
 # Update for pg_bsd_indent version
-my $INDENT_VERSION = "2.1.2";
+my $INDENT_VERSION = "2.1.1";
 
 # Our standard indent settings
 my $indent_opts =
-- 
2.34.1

From 3934621f6aaf2659e38691f7519738ad53fd7e99 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v30 3/5] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 687 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 935 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..952e458c53b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba77..15ae94cc90f 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..477150ac802
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,687 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "verify_common.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrepencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+}			GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* GiST state */
+	GISTSTATE  *state;
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* Debug counter for reporting percentage of work already done */
+	int64		heaptuplespresent;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int			leafdepth;
+}			GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void giststate_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+* Initaliaze GIST state filed needed to perform.
+* This initialized bloom filter and snapshot.
+*/
+static void
+giststate_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * This check allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		giststate_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot, /* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the parent.
+		 */
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
+			 */
+
+			pfree(tmpTuple);
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+												  stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+					 stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+						Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			/* Datum old = compatt[i]; */
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/*
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.34.1

From e695d157c919fa5dfc5ba34b43620d18a595b899 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v30 5/5] Add GiST support to pg_amcheck

Proof of concept patch for pg_amcheck binary support
for GIST and GIN index checks.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 290 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 ++++--
 3 files changed, 220 insertions(+), 143 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 27a7d5e925e..8146ea1e604 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -40,8 +40,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -75,10 +74,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -99,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -135,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -152,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -179,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -196,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -288,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -323,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -382,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -531,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -599,36 +606,32 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension.
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("option %s is not supported by amcheck version %s",
-							   "--checkunique", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("option %s is not supported by amcheck version %s",
+						   "--checkunique", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -650,8 +653,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -784,13 +787,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -868,7 +887,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -914,6 +933,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -953,7 +994,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1103,11 +1144,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1116,7 +1157,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1127,12 +1168,12 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -1142,7 +1183,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1156,7 +1197,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1210,6 +1251,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1423,11 +1466,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1462,14 +1505,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1498,17 +1541,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1766,7 +1809,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1808,7 +1851,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1846,8 +1889,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1870,7 +1913,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1897,7 +1940,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1907,7 +1950,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1915,36 +1958,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1983,7 +2026,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ("
 						  CppAsString2(RELKIND_RELATION) ", "
 						  CppAsString2(RELKIND_SEQUENCE) ", "
@@ -1995,10 +2038,10 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  CppAsString2(RELKIND_SEQUENCE) ", "
 						  CppAsString2(RELKIND_MATVIEW) ", "
 						  CppAsString2(RELKIND_TOASTVALUE) ")) OR "
-						  "(c.relam = %u AND c.relkind = "
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = "
 						  CppAsString2(RELKIND_INDEX) "))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2027,7 +2070,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2035,9 +2078,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2050,15 +2093,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = " CppAsString2(RELKIND_INDEX),
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2066,7 +2109,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2087,7 +2130,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -2107,12 +2150,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2121,29 +2165,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast");
-	if (!opts.no_btree_expansion)
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2163,8 +2207,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2174,15 +2219,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2204,10 +2251,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2217,7 +2265,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 2b57c4dbac1..0aa66b24258 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: option --checkunique is not supported by amcheck version 1.3/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.34.1

From ef5acedd5e02d35925985cf6b166877a54d4788c Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v31 5/5] Add GiST support to pg_amcheck

Proof of concept patch for pg_amcheck binary support
for GIST and GIN index checks.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 290 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 ++++--
 3 files changed, 220 insertions(+), 143 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 27a7d5e925e..8146ea1e604 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -40,8 +40,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -75,10 +74,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -99,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -135,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -152,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -179,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -196,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -288,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -323,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -382,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -531,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -599,36 +606,32 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension.
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("option %s is not supported by amcheck version %s",
-							   "--checkunique", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("option %s is not supported by amcheck version %s",
+						   "--checkunique", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -650,8 +653,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -784,13 +787,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -868,7 +887,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -914,6 +933,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -953,7 +994,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1103,11 +1144,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1116,7 +1157,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1127,12 +1168,12 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -1142,7 +1183,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1156,7 +1197,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1210,6 +1251,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1423,11 +1466,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1462,14 +1505,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1498,17 +1541,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1766,7 +1809,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1808,7 +1851,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1846,8 +1889,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1870,7 +1913,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1897,7 +1940,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1907,7 +1950,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1915,36 +1958,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1983,7 +2026,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ("
 						  CppAsString2(RELKIND_RELATION) ", "
 						  CppAsString2(RELKIND_SEQUENCE) ", "
@@ -1995,10 +2038,10 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  CppAsString2(RELKIND_SEQUENCE) ", "
 						  CppAsString2(RELKIND_MATVIEW) ", "
 						  CppAsString2(RELKIND_TOASTVALUE) ")) OR "
-						  "(c.relam = %u AND c.relkind = "
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = "
 						  CppAsString2(RELKIND_INDEX) "))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2027,7 +2070,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2035,9 +2078,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2050,15 +2093,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = " CppAsString2(RELKIND_INDEX),
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2066,7 +2109,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2087,7 +2130,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -2107,12 +2150,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2121,29 +2165,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast");
-	if (!opts.no_btree_expansion)
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2163,8 +2207,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2174,15 +2219,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2204,10 +2251,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2217,7 +2265,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 2b57c4dbac1..0aa66b24258 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: option --checkunique is not supported by amcheck version 1.3/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.34.1

From 5cb507ead70de64cd966821045a77ae25ef2433a Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v31 2/5] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..1b38e0aba77 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..acdcf5729f7
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index c76349bf436..1da4f0c3461 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.34.1

From e78bc24a3a355c5731cb677b89456ceb9fbd9b55 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v31 1/5] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index ffe4f721672..c76349bf436 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.34.1

From fab0d9c48801247cfc75a92f0a5cb2dd945c11cc Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v31 4/5] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 755 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 src/tools/pgindent/pgindent            |   2 +-
 8 files changed, 892 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 952e458c53b..c01f8e618f3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..c013abc4f55 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90f..5c9ddfe0758 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..ddf072d468d
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,755 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+			{
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			}
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				elog(DEBUG3, "key (%u, %u) -> %u",
+					 ItemPointerGetBlockNumber(&posting_item->key),
+					 ItemPointerGetOffsetNumber(&posting_item->key),
+					 BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = GinPageGetOpaque(page)->maxoff;
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected");
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						* Check if it is properly adjusted.
+						* If succeed, procced to the next key.
+						*/
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..55f2b587e57 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
diff --git a/src/tools/pgindent/pgindent b/src/tools/pgindent/pgindent
index e889af6b1e4..e5ac0410665 100755
--- a/src/tools/pgindent/pgindent
+++ b/src/tools/pgindent/pgindent
@@ -13,7 +13,7 @@ use IO::Handle;
 use Getopt::Long;
 
 # Update for pg_bsd_indent version
-my $INDENT_VERSION = "2.1.2";
+my $INDENT_VERSION = "2.1.1";
 
 # Our standard indent settings
 my $indent_opts =
-- 
2.34.1

From 3934621f6aaf2659e38691f7519738ad53fd7e99 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v31 3/5] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 687 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 935 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..952e458c53b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba77..15ae94cc90f 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..477150ac802
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,687 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "verify_common.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrepencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+}			GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* GiST state */
+	GISTSTATE  *state;
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* Debug counter for reporting percentage of work already done */
+	int64		heaptuplespresent;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int			leafdepth;
+}			GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void giststate_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+* Initaliaze GIST state filed needed to perform.
+* This initialized bloom filter and snapshot.
+*/
+static void
+giststate_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * This check allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		giststate_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot, /* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the parent.
+		 */
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
+			 */
+
+			pfree(tmpTuple);
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+												  stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+					 stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+						Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			/* Datum old = compatt[i]; */
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/*
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.34.1

From b6ae0cee36ba03d060502a89d11dbbed17b3b10f Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v32 5/5] Add GiST support to pg_amcheck

Proof of concept patch for pg_amcheck binary support
for GIST and GIN index checks.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 290 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 ++++--
 3 files changed, 220 insertions(+), 143 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 27a7d5e925e..8146ea1e604 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -40,8 +40,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -75,10 +74,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -99,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -135,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -152,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -179,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -196,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -288,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -323,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -382,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -531,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -599,36 +606,32 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension.
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("option %s is not supported by amcheck version %s",
-							   "--checkunique", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("option %s is not supported by amcheck version %s",
+						   "--checkunique", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -650,8 +653,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -784,13 +787,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -868,7 +887,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -914,6 +933,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -953,7 +994,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1103,11 +1144,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1116,7 +1157,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1127,12 +1168,12 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -1142,7 +1183,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1156,7 +1197,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1210,6 +1251,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1423,11 +1466,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1462,14 +1505,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1498,17 +1541,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1766,7 +1809,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1808,7 +1851,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1846,8 +1889,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1870,7 +1913,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1897,7 +1940,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1907,7 +1950,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1915,36 +1958,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1983,7 +2026,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ("
 						  CppAsString2(RELKIND_RELATION) ", "
 						  CppAsString2(RELKIND_SEQUENCE) ", "
@@ -1995,10 +2038,10 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  CppAsString2(RELKIND_SEQUENCE) ", "
 						  CppAsString2(RELKIND_MATVIEW) ", "
 						  CppAsString2(RELKIND_TOASTVALUE) ")) OR "
-						  "(c.relam = %u AND c.relkind = "
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = "
 						  CppAsString2(RELKIND_INDEX) "))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2027,7 +2070,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2035,9 +2078,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2050,15 +2093,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = " CppAsString2(RELKIND_INDEX),
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2066,7 +2109,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2087,7 +2130,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -2107,12 +2150,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2121,29 +2165,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast");
-	if (!opts.no_btree_expansion)
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2163,8 +2207,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2174,15 +2219,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2204,10 +2251,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2217,7 +2265,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 2b57c4dbac1..0aa66b24258 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: option --checkunique is not supported by amcheck version 1.3/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.34.1

From 5cb507ead70de64cd966821045a77ae25ef2433a Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v32 2/5] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..1b38e0aba77 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..acdcf5729f7
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index c76349bf436..1da4f0c3461 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.34.1

From e78bc24a3a355c5731cb677b89456ceb9fbd9b55 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v32 1/5] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index ffe4f721672..c76349bf436 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.34.1

From a73e5c5fabd5401f6b4ddffadb5b7fb5a4a752a0 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v32 4/5] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 +++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 767 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 src/tools/pgindent/pgindent            |   2 +-
 8 files changed, 904 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 952e458c53b..c01f8e618f3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..c013abc4f55 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90f..5c9ddfe0758 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..e18adf3d1c7
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,767 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[100];
+
+			ItemPointerSetMin(&minItem);
+
+			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			Assert(GinPageIsData(page));
+			maxoff = GinPageGetOpaque(page)->maxoff;
+
+			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				/* ItemPointerGetOffsetNumber expects a valid pointer */
+				if (!(i == maxoff &&
+					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 ItemPointerGetBlockNumber(&posting_item->key),
+						 ItemPointerGetOffsetNumber(&posting_item->key),
+						 BlockIdGetBlockNumber(&posting_item->child_blkno));
+				else
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		elog(DEBUG3, "processing entry tree page at blk %u, maxoff: %u", stack->blkno, maxoff);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (GinPageGetOpaque(page)->rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected for blk: %u, parent blk: %u", stack->blkno, stack->parentblk);
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = GinPageGetOpaque(page)->rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/* (apparently) first block is metadata, skip order check */
+			if (i != FirstOffsetNumber && stack->blkno != (BlockNumber) 1)
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						 * Check if it is properly adjusted. If succeed,
+						 * procced to the next key.
+						 */
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..55f2b587e57 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
diff --git a/src/tools/pgindent/pgindent b/src/tools/pgindent/pgindent
index e889af6b1e4..e5ac0410665 100755
--- a/src/tools/pgindent/pgindent
+++ b/src/tools/pgindent/pgindent
@@ -13,7 +13,7 @@ use IO::Handle;
 use Getopt::Long;
 
 # Update for pg_bsd_indent version
-my $INDENT_VERSION = "2.1.2";
+my $INDENT_VERSION = "2.1.1";
 
 # Our standard indent settings
 my $indent_opts =
-- 
2.34.1

From 3934621f6aaf2659e38691f7519738ad53fd7e99 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v32 3/5] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 687 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 935 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..952e458c53b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba77..15ae94cc90f 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..477150ac802
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,687 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "verify_common.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrepencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+}			GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* GiST state */
+	GISTSTATE  *state;
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* Debug counter for reporting percentage of work already done */
+	int64		heaptuplespresent;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int			leafdepth;
+}			GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void giststate_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+* Initaliaze GIST state filed needed to perform.
+* This initialized bloom filter and snapshot.
+*/
+static void
+giststate_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * This check allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		giststate_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot, /* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the parent.
+		 */
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
+			 */
+
+			pfree(tmpTuple);
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+												  stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+					 stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+						Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			/* Datum old = compatt[i]; */
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/*
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.34.1

From 3380a7148a5c20f2da6d6d8c1d0f8693e518ccec Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v33 3/5] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 687 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 935 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..952e458c53b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 1b38e0aba77..15ae94cc90f 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..477150ac802
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,687 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "verify_common.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrepencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+}			GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* GiST state */
+	GISTSTATE  *state;
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* Debug counter for reporting percentage of work already done */
+	int64		heaptuplespresent;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int			leafdepth;
+}			GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void giststate_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+* Initaliaze GIST state filed needed to perform.
+* This initialized bloom filter and snapshot.
+*/
+static void
+giststate_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * This check allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		giststate_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot, /* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the parent.
+		 */
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
+			 */
+
+			pfree(tmpTuple);
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+												  stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+					 stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+						Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			/* Datum old = compatt[i]; */
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/*
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.34.1

From a73f5e5f73d9a0c12cc29c4b349950a6fe3ead36 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v33 1/5] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index ffe4f721672..c76349bf436 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.34.1

From 8870ff60fd743e090ebf86426a5b2bd76798af29 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v33 2/5] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..1b38e0aba77 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'amcheck.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..acdcf5729f7
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index c76349bf436..1da4f0c3461 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.34.1

From 2970cfbdee597aee3d5122c4f8447a7f18dcbff2 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v33 4/5] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 774 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 src/tools/pgindent/pgindent            |   2 +-
 8 files changed, 911 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 952e458c53b..c01f8e618f3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..c013abc4f55 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 15ae94cc90f..5c9ddfe0758 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'amcheck.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..2dc5fbba619
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,774 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[MAXPGPATH];
+
+			ItemPointerSetMin(&minItem);
+
+			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			Assert(GinPageIsData(page));
+			maxoff = GinPageGetOpaque(page)->maxoff;
+
+			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				/* ItemPointerGetOffsetNumber expects a valid pointer */
+				if (!(i == maxoff &&
+					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 ItemPointerGetBlockNumber(&posting_item->key),
+						 ItemPointerGetOffsetNumber(&posting_item->key),
+						 BlockIdGetBlockNumber(&posting_item->child_blkno));
+				else
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+		BlockNumber rightlink;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+		rightlink = GinPageGetOpaque(page)->rightlink;
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		elog(DEBUG3, "processing entry tree page at blk %u, maxoff: %u", stack->blkno, maxoff);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected for blk: %u, parent blk: %u", stack->blkno, stack->parentblk);
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/*
+			 * First block is metadata, skip order check. Also, never check
+			 * for high key on rightmost page, as this key is not really
+			 * stored explicitly.
+			 */
+			if (i != FirstOffsetNumber && stack->blkno != GIN_ROOT_BLKNO &&
+				!(i == maxoff && rightlink == InvalidBlockNumber))
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						 * Check if it is properly adjusted. If succeed,
+						 * procced to the next key.
+						 */
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..55f2b587e57 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
diff --git a/src/tools/pgindent/pgindent b/src/tools/pgindent/pgindent
index e889af6b1e4..e5ac0410665 100755
--- a/src/tools/pgindent/pgindent
+++ b/src/tools/pgindent/pgindent
@@ -13,7 +13,7 @@ use IO::Handle;
 use Getopt::Long;
 
 # Update for pg_bsd_indent version
-my $INDENT_VERSION = "2.1.2";
+my $INDENT_VERSION = "2.1.1";
 
 # Our standard indent settings
 my $indent_opts =
-- 
2.34.1

From 544e53f83acc78c07488cb315359b1a5bef4d72d Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v33 5/5] Add GiST support to pg_amcheck

Proof of concept patch for pg_amcheck binary support
for GIST and GIN index checks.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 290 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 ++++--
 3 files changed, 220 insertions(+), 143 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 27a7d5e925e..8146ea1e604 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -40,8 +40,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -75,10 +74,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -99,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -135,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -152,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -179,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -196,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -288,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -323,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -382,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -531,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -599,36 +606,32 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension.
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("option %s is not supported by amcheck version %s",
-							   "--checkunique", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("option %s is not supported by amcheck version %s",
+						   "--checkunique", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -650,8 +653,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -784,13 +787,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -868,7 +887,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -914,6 +933,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -953,7 +994,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1103,11 +1144,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1116,7 +1157,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1127,12 +1168,12 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -1142,7 +1183,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1156,7 +1197,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1210,6 +1251,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1423,11 +1466,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1462,14 +1505,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1498,17 +1541,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1766,7 +1809,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1808,7 +1851,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1846,8 +1889,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1870,7 +1913,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1897,7 +1940,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1907,7 +1950,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1915,36 +1958,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1983,7 +2026,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ("
 						  CppAsString2(RELKIND_RELATION) ", "
 						  CppAsString2(RELKIND_SEQUENCE) ", "
@@ -1995,10 +2038,10 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  CppAsString2(RELKIND_SEQUENCE) ", "
 						  CppAsString2(RELKIND_MATVIEW) ", "
 						  CppAsString2(RELKIND_TOASTVALUE) ")) OR "
-						  "(c.relam = %u AND c.relkind = "
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = "
 						  CppAsString2(RELKIND_INDEX) "))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2027,7 +2070,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2035,9 +2078,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2050,15 +2093,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = " CppAsString2(RELKIND_INDEX),
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2066,7 +2109,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2087,7 +2130,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -2107,12 +2150,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2121,29 +2165,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast");
-	if (!opts.no_btree_expansion)
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2163,8 +2207,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2174,15 +2219,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2204,10 +2251,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2217,7 +2265,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 2b57c4dbac1..0aa66b24258 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: option --checkunique is not supported by amcheck version 1.3/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.34.1

From 5c9ffe515d681ece28741a4d469a3f9120dcc255 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 3 Dec 2024 15:02:47 +0000
Subject: [PATCH v33 6/6] Fix wording in GIN README.

---
 src/backend/access/gin/README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/gin/README b/src/backend/access/gin/README
index b0807316212..742bcbad499 100644
--- a/src/backend/access/gin/README
+++ b/src/backend/access/gin/README
@@ -237,10 +237,10 @@ GIN packs keys and downlinks into tuples in a different way.
 
 P_i is grouped with K_{i+1}.  -Inf key is not needed.
 
-There are couple of additional notes regarding K_{n+1} key.
-1) In entry tree rightmost page, a key coupled with P_n doesn't really matter.
+There are a couple of additional notes regarding K_{n+1} key.
+1) In the entry tree on the rightmost page, a key coupled with P_n doesn't really matter.
 Highkey is assumed to be infinity.
-2) In posting tree, a key coupled with P_n always doesn't matter.  Highkey for
+2) In the posting tree, a key coupled with P_n always doesn't matter.  Highkey for
 non-rightmost pages is stored separately and accessed via
 GinDataPageGetRightBound().
 
-- 
2.34.1

From a73f5e5f73d9a0c12cc29c4b349950a6fe3ead36 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v34 1/6] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index ffe4f721672..c76349bf436 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.34.1

From 241fddea9e97f92aec76bfef7d7338f15e4f08a5 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:22:26 +0500
Subject: [PATCH v34 4/6] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   3 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |   9 +
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   2 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 774 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  19 +
 src/tools/pgindent/pgindent            |   2 +-
 8 files changed, 911 insertions(+), 2 deletions(-)
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 952e458c53b..c01f8e618f3 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,6 +4,7 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
@@ -13,7 +14,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gist check_heap
+REGRESS = check check_btree check_gin check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
index 3fc72364180..c013abc4f55 100644
--- a/contrib/amcheck/amcheck--1.4--1.5.sql
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -12,3 +12,12 @@ AS 'MODULE_PATHNAME', 'gist_index_check'
 LANGUAGE C STRICT;
 
 REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 5ab83ca7778..cbe15f4244c 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'verify_common.c',
+  'verify_gin.c',
   'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
@@ -38,6 +39,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_gist',
       'check_heap',
     ],
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..2dc5fbba619
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,774 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[MAXPGPATH];
+
+			ItemPointerSetMin(&minItem);
+
+			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			Assert(GinPageIsData(page));
+			maxoff = GinPageGetOpaque(page)->maxoff;
+
+			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				/* ItemPointerGetOffsetNumber expects a valid pointer */
+				if (!(i == maxoff &&
+					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 ItemPointerGetBlockNumber(&posting_item->key),
+						 ItemPointerGetOffsetNumber(&posting_item->key),
+						 BlockIdGetBlockNumber(&posting_item->child_blkno));
+				else
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+		BlockNumber rightlink;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+		rightlink = GinPageGetOpaque(page)->rightlink;
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		elog(DEBUG3, "processing entry tree page at blk %u, maxoff: %u", stack->blkno, maxoff);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected for blk: %u, parent blk: %u", stack->blkno, stack->parentblk);
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/*
+			 * First block is metadata, skip order check. Also, never check
+			 * for high key on rightmost page, as this key is not really
+			 * stored explicitly.
+			 */
+			if (i != FirstOffsetNumber && stack->blkno != GIN_ROOT_BLKNO &&
+				!(i == maxoff && rightlink == InvalidBlockNumber))
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						 * Check if it is properly adjusted. If succeed,
+						 * procced to the next key.
+						 */
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 6eb526c6bb7..55f2b587e57 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -189,6 +189,25 @@ ORDER BY c.relpages DESC LIMIT 10;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term>
      <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
diff --git a/src/tools/pgindent/pgindent b/src/tools/pgindent/pgindent
index e889af6b1e4..e5ac0410665 100755
--- a/src/tools/pgindent/pgindent
+++ b/src/tools/pgindent/pgindent
@@ -13,7 +13,7 @@ use IO::Handle;
 use Getopt::Long;
 
 # Update for pg_bsd_indent version
-my $INDENT_VERSION = "2.1.2";
+my $INDENT_VERSION = "2.1.1";
 
 # Our standard indent settings
 my $indent_opts =
-- 
2.34.1

From a048ec57335f109d18ed947e2aa3458ec40ec9af Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:08:10 +0500
Subject: [PATCH v34 2/6] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru

fix
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index fc08e32539a..6a1ba5d7619 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2024, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'verify_common.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..c8ed685ba42
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_common.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_common.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index c76349bf436..1da4f0c3461 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.34.1

From 32bf8f47535cef157572e42307f69fcac33a0615 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sun, 5 Feb 2023 15:52:14 -0800
Subject: [PATCH v34 5/6] Add GiST support to pg_amcheck

Proof of concept patch for pg_amcheck binary support
for GIST and GIN index checks.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
---
 src/bin/pg_amcheck/pg_amcheck.c      | 290 ++++++++++++++++-----------
 src/bin/pg_amcheck/t/002_nonesuch.pl |   8 +-
 src/bin/pg_amcheck/t/003_check.pl    |  65 ++++--
 3 files changed, 220 insertions(+), 143 deletions(-)

diff --git a/src/bin/pg_amcheck/pg_amcheck.c b/src/bin/pg_amcheck/pg_amcheck.c
index 27a7d5e925e..8146ea1e604 100644
--- a/src/bin/pg_amcheck/pg_amcheck.c
+++ b/src/bin/pg_amcheck/pg_amcheck.c
@@ -40,8 +40,7 @@ typedef struct PatternInfo
 								 * NULL */
 	bool		heap_only;		/* true if rel_regex should only match heap
 								 * tables */
-	bool		btree_only;		/* true if rel_regex should only match btree
-								 * indexes */
+	bool		index_only;		/* true if rel_regex should only match indexes */
 	bool		matched;		/* true if the pattern matched in any database */
 } PatternInfo;
 
@@ -75,10 +74,9 @@ typedef struct AmcheckOptions
 
 	/*
 	 * As an optimization, if any pattern in the exclude list applies to heap
-	 * tables, or similarly if any such pattern applies to btree indexes, or
-	 * to schemas, then these will be true, otherwise false.  These should
-	 * always agree with what you'd conclude by grep'ing through the exclude
-	 * list.
+	 * tables, or similarly if any such pattern applies to indexes, or to
+	 * schemas, then these will be true, otherwise false.  These should always
+	 * agree with what you'd conclude by grep'ing through the exclude list.
 	 */
 	bool		excludetbl;
 	bool		excludeidx;
@@ -99,14 +97,14 @@ typedef struct AmcheckOptions
 	int64		endblock;
 	const char *skip;
 
-	/* btree index checking options */
+	/* index checking options */
 	bool		parent_check;
 	bool		rootdescend;
 	bool		heapallindexed;
 	bool		checkunique;
 
-	/* heap and btree hybrid option */
-	bool		no_btree_expansion;
+	/* heap and indexes hybrid option */
+	bool		no_index_expansion;
 } AmcheckOptions;
 
 static AmcheckOptions opts = {
@@ -135,7 +133,7 @@ static AmcheckOptions opts = {
 	.rootdescend = false,
 	.heapallindexed = false,
 	.checkunique = false,
-	.no_btree_expansion = false
+	.no_index_expansion = false
 };
 
 static const char *progname = NULL;
@@ -152,13 +150,15 @@ typedef struct DatabaseInfo
 	char	   *datname;
 	char	   *amcheck_schema; /* escaped, quoted literal */
 	bool		is_checkunique;
+	bool		gist_supported;
 } DatabaseInfo;
 
 typedef struct RelationInfo
 {
 	const DatabaseInfo *datinfo;	/* shared by other relinfos */
 	Oid			reloid;
-	bool		is_heap;		/* true if heap, false if btree */
+	Oid			amoid;
+	bool		is_heap;		/* true if heap, false if index */
 	char	   *nspname;
 	char	   *relname;
 	int			relpages;
@@ -179,10 +179,12 @@ static void prepare_heap_command(PQExpBuffer sql, RelationInfo *rel,
 								 PGconn *conn);
 static void prepare_btree_command(PQExpBuffer sql, RelationInfo *rel,
 								  PGconn *conn);
+static void prepare_gist_command(PQExpBuffer sql, RelationInfo *rel,
+								 PGconn *conn);
 static void run_command(ParallelSlot *slot, const char *sql);
 static bool verify_heap_slot_handler(PGresult *res, PGconn *conn,
 									 void *context);
-static bool verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context);
+static bool verify_index_slot_handler(PGresult *res, PGconn *conn, void *context);
 static void help(const char *progname);
 static void progress_report(uint64 relations_total, uint64 relations_checked,
 							uint64 relpages_total, uint64 relpages_checked,
@@ -196,7 +198,7 @@ static void append_relation_pattern(PatternInfoArray *pia, const char *pattern,
 									int encoding);
 static void append_heap_pattern(PatternInfoArray *pia, const char *pattern,
 								int encoding);
-static void append_btree_pattern(PatternInfoArray *pia, const char *pattern,
+static void append_index_pattern(PatternInfoArray *pia, const char *pattern,
 								 int encoding);
 static void compile_database_list(PGconn *conn, SimplePtrList *databases,
 								  const char *initial_dbname);
@@ -288,6 +290,7 @@ main(int argc, char *argv[])
 	enum trivalue prompt_password = TRI_DEFAULT;
 	int			encoding = pg_get_encoding_from_locale(NULL, false);
 	ConnParams	cparams;
+	bool		gist_warn_printed = false;
 
 	pg_logging_init(argv[0]);
 	progname = get_progname(argv[0]);
@@ -323,11 +326,11 @@ main(int argc, char *argv[])
 				break;
 			case 'i':
 				opts.allrel = false;
-				append_btree_pattern(&opts.include, optarg, encoding);
+				append_index_pattern(&opts.include, optarg, encoding);
 				break;
 			case 'I':
 				opts.excludeidx = true;
-				append_btree_pattern(&opts.exclude, optarg, encoding);
+				append_index_pattern(&opts.exclude, optarg, encoding);
 				break;
 			case 'j':
 				if (!option_parse_int(optarg, "-j/--jobs", 1, INT_MAX,
@@ -382,7 +385,7 @@ main(int argc, char *argv[])
 				maintenance_db = pg_strdup(optarg);
 				break;
 			case 2:
-				opts.no_btree_expansion = true;
+				opts.no_index_expansion = true;
 				break;
 			case 3:
 				opts.no_toast_expansion = true;
@@ -531,6 +534,10 @@ main(int argc, char *argv[])
 		int			ntups;
 		const char *amcheck_schema = NULL;
 		DatabaseInfo *dat = (DatabaseInfo *) cell->ptr;
+		int			vmaj = 0,
+					vmin = 0,
+					vrev = 0;
+		const char *amcheck_version;
 
 		cparams.override_dbname = dat->datname;
 		if (conn == NULL || strcmp(PQdb(conn), dat->datname) != 0)
@@ -599,36 +606,32 @@ main(int argc, char *argv[])
 												 strlen(amcheck_schema));
 
 		/*
-		 * Check the version of amcheck extension. Skip requested unique
-		 * constraint check with warning if it is not yet supported by
-		 * amcheck.
+		 * Check the version of amcheck extension.
 		 */
-		if (opts.checkunique == true)
-		{
-			/*
-			 * Now amcheck has only major and minor versions in the string but
-			 * we also support revision just in case. Now it is expected to be
-			 * zero.
-			 */
-			int			vmaj = 0,
-						vmin = 0,
-						vrev = 0;
-			const char *amcheck_version = PQgetvalue(result, 0, 1);
+		amcheck_version = PQgetvalue(result, 0, 1);
 
-			sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
+		/*
+		 * Now amcheck has only major and minor versions in the string but we
+		 * also support revision just in case. Now it is expected to be zero.
+		 */
+		sscanf(amcheck_version, "%d.%d.%d", &vmaj, &vmin, &vrev);
 
-			/*
-			 * checkunique option is supported in amcheck since version 1.4
-			 */
-			if ((vmaj == 1 && vmin < 4) || vmaj == 0)
-			{
-				pg_log_warning("option %s is not supported by amcheck version %s",
-							   "--checkunique", amcheck_version);
-				dat->is_checkunique = false;
-			}
-			else
-				dat->is_checkunique = true;
+		/*
+		 * checkunique option is supported in amcheck since version 1.4. Skip
+		 * requested unique constraint check with warning if it is not yet
+		 * supported by amcheck.
+		 */
+		if (opts.checkunique && ((vmaj == 1 && vmin < 4) || vmaj == 0))
+		{
+			pg_log_warning("option %s is not supported by amcheck version %s",
+						   "--checkunique", amcheck_version);
+			dat->is_checkunique = false;
 		}
+		else
+			dat->is_checkunique = opts.checkunique;
+
+		/* GiST indexes are supported in 1.5+ */
+		dat->gist_supported = ((vmaj == 1 && vmin >= 5) || vmaj > 1);
 
 		PQclear(result);
 
@@ -650,8 +653,8 @@ main(int argc, char *argv[])
 			if (pat->heap_only)
 				log_no_match("no heap tables to check matching \"%s\"",
 							 pat->pattern);
-			else if (pat->btree_only)
-				log_no_match("no btree indexes to check matching \"%s\"",
+			else if (pat->index_only)
+				log_no_match("no indexes to check matching \"%s\"",
 							 pat->pattern);
 			else if (pat->rel_regex == NULL)
 				log_no_match("no relations to check in schemas matching \"%s\"",
@@ -784,13 +787,29 @@ main(int argc, char *argv[])
 				if (opts.show_progress && progress_since_last_stderr)
 					fprintf(stderr, "\n");
 
-				pg_log_info("checking btree index \"%s.%s.%s\"",
+				pg_log_info("checking index \"%s.%s.%s\"",
 							rel->datinfo->datname, rel->nspname, rel->relname);
 				progress_since_last_stderr = false;
 			}
-			prepare_btree_command(&sql, rel, free_slot->connection);
+			if (rel->amoid == BTREE_AM_OID)
+				prepare_btree_command(&sql, rel, free_slot->connection);
+			else if (rel->amoid == GIST_AM_OID)
+			{
+				if (rel->datinfo->gist_supported)
+					prepare_gist_command(&sql, rel, free_slot->connection);
+				else
+				{
+					if (!gist_warn_printed)
+						pg_log_warning("GiST verification is not supported by installed amcheck version");
+					gist_warn_printed = true;
+				}
+			}
+			else
+				/* should not happen at this stage */
+				pg_log_info("Verification of index type %u not supported",
+							rel->amoid);
 			rel->sql = pstrdup(sql.data);	/* pg_free'd after command */
-			ParallelSlotSetHandler(free_slot, verify_btree_slot_handler, rel);
+			ParallelSlotSetHandler(free_slot, verify_index_slot_handler, rel);
 			run_command(free_slot, rel->sql);
 		}
 	}
@@ -868,7 +887,7 @@ prepare_heap_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
  * Creates a SQL command for running amcheck checking on the given btree index
  * relation.  The command does not select any columns, as btree checking
  * functions do not return any, but rather return corruption information by
- * raising errors, which verify_btree_slot_handler expects.
+ * raising errors, which verify_index_slot_handler expects.
  *
  * The constructed SQL command will silently skip temporary indexes, and
  * indexes being reindexed concurrently, as checking them would needlessly draw
@@ -914,6 +933,28 @@ prepare_btree_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
 						  rel->reloid);
 }
 
+/*
+ * prepare_gist_command
+ * Similar to btree equivalent prepares command to check GiST index.
+ */
+static void
+prepare_gist_command(PQExpBuffer sql, RelationInfo *rel, PGconn *conn)
+{
+	resetPQExpBuffer(sql);
+
+	appendPQExpBuffer(sql,
+					  "SELECT %s.gist_index_check("
+					  "index := c.oid, heapallindexed := %s)"
+					  "\nFROM pg_catalog.pg_class c, pg_catalog.pg_index i "
+					  "WHERE c.oid = %u "
+					  "AND c.oid = i.indexrelid "
+					  "AND c.relpersistence != 't' "
+					  "AND i.indisready AND i.indisvalid AND i.indislive",
+					  rel->datinfo->amcheck_schema,
+					  (opts.heapallindexed ? "true" : "false"),
+					  rel->reloid);
+}
+
 /*
  * run_command
  *
@@ -953,7 +994,7 @@ run_command(ParallelSlot *slot, const char *sql)
  * Note: Heap relation corruption is reported by verify_heapam() via the result
  * set, rather than an ERROR, but running verify_heapam() on a corrupted heap
  * table may still result in an error being returned from the server due to
- * missing relation files, bad checksums, etc.  The btree corruption checking
+ * missing relation files, bad checksums, etc.  The corruption checking
  * functions always use errors to communicate corruption messages.  We can't
  * just abort processing because we got a mere ERROR.
  *
@@ -1103,11 +1144,11 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
 }
 
 /*
- * verify_btree_slot_handler
+ * verify_index_slot_handler
  *
- * ParallelSlotHandler that receives results from a btree checking command
- * created by prepare_btree_command and outputs them for the user.  The results
- * from the btree checking command is assumed to be empty, but when the results
+ * ParallelSlotHandler that receives results from a checking command created by
+ * prepare_[btree,gist]_command and outputs them for the user.  The results
+ * from the checking command is assumed to be empty, but when the results
  * are an error code, the useful information about the corruption is expected
  * in the connection's error message.
  *
@@ -1116,7 +1157,7 @@ verify_heap_slot_handler(PGresult *res, PGconn *conn, void *context)
  * context: unused
  */
 static bool
-verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
+verify_index_slot_handler(PGresult *res, PGconn *conn, void *context)
 {
 	RelationInfo *rel = (RelationInfo *) context;
 
@@ -1127,12 +1168,12 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		if (ntups > 1)
 		{
 			/*
-			 * We expect the btree checking functions to return one void row
-			 * each, or zero rows if the check was skipped due to the object
-			 * being in the wrong state to be checked, so we should output
-			 * some sort of warning if we get anything more, not because it
-			 * indicates corruption, but because it suggests a mismatch
-			 * between amcheck and pg_amcheck versions.
+			 * We expect the checking functions to return one void row each,
+			 * or zero rows if the check was skipped due to the object being
+			 * in the wrong state to be checked, so we should output some sort
+			 * of warning if we get anything more, not because it indicates
+			 * corruption, but because it suggests a mismatch between amcheck
+			 * and pg_amcheck versions.
 			 *
 			 * In conjunction with --progress, anything written to stderr at
 			 * this time would present strangely to the user without an extra
@@ -1142,7 +1183,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 			 */
 			if (opts.show_progress && progress_since_last_stderr)
 				fprintf(stderr, "\n");
-			pg_log_warning("btree index \"%s.%s.%s\": btree checking function returned unexpected number of rows: %d",
+			pg_log_warning("index \"%s.%s.%s\": checking function returned unexpected number of rows: %d",
 						   rel->datinfo->datname, rel->nspname, rel->relname, ntups);
 			if (opts.verbose)
 				pg_log_warning_detail("Query was: %s", rel->sql);
@@ -1156,7 +1197,7 @@ verify_btree_slot_handler(PGresult *res, PGconn *conn, void *context)
 		char	   *msg = indent_lines(PQerrorMessage(conn));
 
 		all_checks_pass = false;
-		printf(_("btree index \"%s.%s.%s\":\n"),
+		printf(_("index \"%s.%s.%s\":\n"),
 			   rel->datinfo->datname, rel->nspname, rel->relname);
 		printf("%s", msg);
 		if (opts.verbose)
@@ -1210,6 +1251,8 @@ help(const char *progname)
 	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("      --parent-check              check index parent/child relationships\n"));
 	printf(_("      --rootdescend               search from root page to refind tuples\n"));
+	printf(_("\nGiST index checking options:\n"));
+	printf(_("      --heapallindexed            check that all heap tuples are found within indexes\n"));
 	printf(_("\nConnection options:\n"));
 	printf(_("  -h, --host=HOSTNAME             database server host or socket directory\n"));
 	printf(_("  -p, --port=PORT                 database server port\n"));
@@ -1423,11 +1466,11 @@ append_schema_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  * heap_only: whether the pattern should only be matched against heap tables
- * btree_only: whether the pattern should only be matched against btree indexes
+ * index_only: whether the pattern should only be matched against indexes
  */
 static void
 append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
-							   int encoding, bool heap_only, bool btree_only)
+							   int encoding, bool heap_only, bool index_only)
 {
 	PQExpBufferData dbbuf;
 	PQExpBufferData nspbuf;
@@ -1462,14 +1505,14 @@ append_relation_pattern_helper(PatternInfoArray *pia, const char *pattern,
 	termPQExpBuffer(&relbuf);
 
 	info->heap_only = heap_only;
-	info->btree_only = btree_only;
+	info->index_only = index_only;
 }
 
 /*
  * append_relation_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched
- * against both heap tables and btree indexes.
+ * against both heap tables and indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
@@ -1498,17 +1541,17 @@ append_heap_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 }
 
 /*
- * append_btree_pattern
+ * append_index_pattern
  *
  * Adds the given pattern interpreted as a relation pattern, to be matched only
- * against btree indexes.
+ * against indexes.
  *
  * pia: the pattern info array to be appended
  * pattern: the relation name pattern
  * encoding: client encoding for parsing the pattern
  */
 static void
-append_btree_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
+append_index_pattern(PatternInfoArray *pia, const char *pattern, int encoding)
 {
 	append_relation_pattern_helper(pia, pattern, encoding, false, true);
 }
@@ -1766,7 +1809,7 @@ compile_database_list(PGconn *conn, SimplePtrList *databases,
  *     rel_regex: the relname regexp parsed from the pattern, or NULL if the
  *                pattern had no relname part
  *     heap_only: true if the pattern applies only to heap tables (not indexes)
- *     btree_only: true if the pattern applies only to btree indexes (not tables)
+ *     index_only: true if the pattern applies only to indexes (not tables)
  *
  * buf: the buffer to be appended
  * patterns: the array of patterns to be inserted into the CTE
@@ -1808,7 +1851,7 @@ append_rel_pattern_raw_cte(PQExpBuffer buf, const PatternInfoArray *pia,
 			appendPQExpBufferStr(buf, "::TEXT, true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, "::TEXT, false::BOOLEAN");
-		if (info->btree_only)
+		if (info->index_only)
 			appendPQExpBufferStr(buf, ", true::BOOLEAN");
 		else
 			appendPQExpBufferStr(buf, ", false::BOOLEAN");
@@ -1846,8 +1889,8 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
 								const char *filtered, PGconn *conn)
 {
 	appendPQExpBuffer(buf,
-					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, btree_only) AS ("
-					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, btree_only "
+					  "\n%s (pattern_id, nsp_regex, rel_regex, heap_only, index_only) AS ("
+					  "\nSELECT pattern_id, nsp_regex, rel_regex, heap_only, index_only "
 					  "FROM %s r"
 					  "\nWHERE (r.db_regex IS NULL "
 					  "OR ",
@@ -1870,7 +1913,7 @@ append_rel_pattern_filtered_cte(PQExpBuffer buf, const char *raw,
  * The cells of the constructed list contain all information about the relation
  * necessary to connect to the database and check the object, including which
  * database to connect to, where contrib/amcheck is installed, and the Oid and
- * type of object (heap table vs. btree index).  Rather than duplicating the
+ * type of object (heap table vs. index).  Rather than duplicating the
  * database details per relation, the relation structs use references to the
  * same database object, provided by the caller.
  *
@@ -1897,7 +1940,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (!opts.allrel)
 	{
 		appendPQExpBufferStr(&sql,
-							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " include_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.include, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "include_raw", "include_pat", conn);
@@ -1907,7 +1950,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 	{
 		appendPQExpBufferStr(&sql,
-							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, btree_only) AS (");
+							 " exclude_raw (pattern_id, db_regex, nsp_regex, rel_regex, heap_only, index_only) AS (");
 		append_rel_pattern_raw_cte(&sql, &opts.exclude, conn);
 		appendPQExpBufferStr(&sql, "\n),");
 		append_rel_pattern_filtered_cte(&sql, "exclude_raw", "exclude_pat", conn);
@@ -1915,36 +1958,36 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 
 	/* Append the relation CTE. */
 	appendPQExpBufferStr(&sql,
-						 " relation (pattern_id, oid, nspname, relname, reltoastrelid, relpages, is_heap, is_btree) AS ("
+						 " relation (pattern_id, oid, amoid, nspname, relname, reltoastrelid, relpages, is_heap, is_index) AS ("
 						 "\nSELECT DISTINCT ON (c.oid");
 	if (!opts.allrel)
 		appendPQExpBufferStr(&sql, ", ip.pattern_id) ip.pattern_id,");
 	else
 		appendPQExpBufferStr(&sql, ") NULL::INTEGER AS pattern_id,");
 	appendPQExpBuffer(&sql,
-					  "\nc.oid, n.nspname, c.relname, c.reltoastrelid, c.relpages, "
-					  "c.relam = %u AS is_heap, "
-					  "c.relam = %u AS is_btree"
+					  "\nc.oid, c.relam as amoid, n.nspname, c.relname, "
+					  "c.reltoastrelid, c.relpages, c.relam = %u AS is_heap, "
+					  "(c.relam = %u OR c.relam = %u) AS is_index"
 					  "\nFROM pg_catalog.pg_class c "
 					  "INNER JOIN pg_catalog.pg_namespace n "
 					  "ON c.relnamespace = n.oid",
-					  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+					  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (!opts.allrel)
 		appendPQExpBuffer(&sql,
 						  "\nINNER JOIN include_pat ip"
 						  "\nON (n.nspname ~ ip.nsp_regex OR ip.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ip.rel_regex OR ip.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ip.heap_only)"
-						  "\nAND (c.relam = %u OR NOT ip.btree_only)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ip.index_only)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 	if (opts.excludetbl || opts.excludeidx || opts.excludensp)
 		appendPQExpBuffer(&sql,
 						  "\nLEFT OUTER JOIN exclude_pat ep"
 						  "\nON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL)"
 						  "\nAND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL)"
 						  "\nAND (c.relam = %u OR NOT ep.heap_only OR ep.rel_regex IS NULL)"
-						  "\nAND (c.relam = %u OR NOT ep.btree_only OR ep.rel_regex IS NULL)",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  "\nAND ((c.relam = %u OR c.relam = %u) OR NOT ep.index_only OR ep.rel_regex IS NULL)",
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	/*
 	 * Exclude temporary tables and indexes, which must necessarily belong to
@@ -1983,7 +2026,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  HEAP_TABLE_AM_OID, PG_TOAST_NAMESPACE);
 	else
 		appendPQExpBuffer(&sql,
-						  " AND c.relam IN (%u, %u)"
+						  " AND c.relam IN (%u, %u, %u)"
 						  "AND c.relkind IN ("
 						  CppAsString2(RELKIND_RELATION) ", "
 						  CppAsString2(RELKIND_SEQUENCE) ", "
@@ -1995,10 +2038,10 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						  CppAsString2(RELKIND_SEQUENCE) ", "
 						  CppAsString2(RELKIND_MATVIEW) ", "
 						  CppAsString2(RELKIND_TOASTVALUE) ")) OR "
-						  "(c.relam = %u AND c.relkind = "
+						  "((c.relam = %u OR c.relam = %u) AND c.relkind = "
 						  CppAsString2(RELKIND_INDEX) "))",
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID,
-						  HEAP_TABLE_AM_OID, BTREE_AM_OID);
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID,
+						  HEAP_TABLE_AM_OID, BTREE_AM_OID, GIST_AM_OID);
 
 	appendPQExpBufferStr(&sql,
 						 "\nORDER BY c.oid)");
@@ -2027,7 +2070,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql,
 							 "\n)");
 	}
-	if (!opts.no_btree_expansion)
+	if (!opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with primary heap tables
@@ -2035,9 +2078,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		 * btree index names.
 		 */
 		appendPQExpBufferStr(&sql,
-							 ", index (oid, nspname, relname, relpages) AS ("
-							 "\nSELECT c.oid, r.nspname, c.relname, c.relpages "
-							 "FROM relation r"
+							 ", index (oid, amoid, nspname, relname, relpages) AS ("
+							 "\nSELECT c.oid, c.relam as amoid, r.nspname, "
+							 "c.relname, c.relpages FROM relation r"
 							 "\nINNER JOIN pg_catalog.pg_index i "
 							 "ON r.oid = i.indrelid "
 							 "INNER JOIN pg_catalog.pg_class c "
@@ -2050,15 +2093,15 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON (n.nspname ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only"
+								 "AND ep.index_only"
 								 "\nWHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
 								 "\nWHERE true");
 		appendPQExpBuffer(&sql,
-						  " AND c.relam = %u "
+						  " AND (c.relam = %u or c.relam = %u) "
 						  "AND c.relkind = " CppAsString2(RELKIND_INDEX),
-						  BTREE_AM_OID);
+						  BTREE_AM_OID, GIST_AM_OID);
 		if (opts.no_toast_expansion)
 			appendPQExpBuffer(&sql,
 							  " AND c.relnamespace != %u",
@@ -2066,7 +2109,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		appendPQExpBufferStr(&sql, "\n)");
 	}
 
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
 	{
 		/*
 		 * Include a CTE for btree indexes associated with toast tables of
@@ -2087,7 +2130,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 								 "\nLEFT OUTER JOIN exclude_pat ep "
 								 "ON ('pg_toast' ~ ep.nsp_regex OR ep.nsp_regex IS NULL) "
 								 "AND (c.relname ~ ep.rel_regex OR ep.rel_regex IS NULL) "
-								 "AND ep.btree_only "
+								 "AND ep.index_only "
 								 "WHERE ep.pattern_id IS NULL");
 		else
 			appendPQExpBufferStr(&sql,
@@ -2107,12 +2150,13 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	 * list.
 	 */
 	appendPQExpBufferStr(&sql,
-						 "\nSELECT pattern_id, is_heap, is_btree, oid, nspname, relname, relpages "
+						 "\nSELECT pattern_id, is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM (");
 	appendPQExpBufferStr(&sql,
 	/* Inclusion patterns that failed to match */
-						 "\nSELECT pattern_id, is_heap, is_btree, "
+						 "\nSELECT pattern_id, is_heap, is_index, "
 						 "NULL::OID AS oid, "
+						 "NULL::OID AS amoid, "
 						 "NULL::TEXT AS nspname, "
 						 "NULL::TEXT AS relname, "
 						 "NULL::INTEGER AS relpages"
@@ -2121,29 +2165,29 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 						 "UNION"
 	/* Primary relations */
 						 "\nSELECT NULL::INTEGER AS pattern_id, "
-						 "is_heap, is_btree, oid, nspname, relname, relpages "
+						 "is_heap, is_index, oid, amoid, nspname, relname, relpages "
 						 "FROM relation");
 	if (!opts.no_toast_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Toast tables for primary relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
-							 "FALSE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast");
-	if (!opts.no_btree_expansion)
+						  "\nSELECT NULL::INTEGER AS pattern_id, TRUE AS is_heap, "
+						  "FALSE AS is_index, oid, 0 as amoid, nspname, relname, relpages "
+						  "FROM toast");
+	if (!opts.no_index_expansion)
 		appendPQExpBufferStr(&sql,
 							 " UNION"
 		/* Indexes for primary relations */
 							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
+							 "TRUE AS is_index, oid, amoid, nspname, relname, relpages "
 							 "FROM index");
-	if (!opts.no_toast_expansion && !opts.no_btree_expansion)
-		appendPQExpBufferStr(&sql,
-							 " UNION"
+	if (!opts.no_toast_expansion && !opts.no_index_expansion)
+		appendPQExpBuffer(&sql,
+						  " UNION"
 		/* Indexes for toast relations */
-							 "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
-							 "TRUE AS is_btree, oid, nspname, relname, relpages "
-							 "FROM toast_index");
+						  "\nSELECT NULL::INTEGER AS pattern_id, FALSE AS is_heap, "
+						  "TRUE AS is_index, oid, %u as amoid, nspname, relname, relpages "
+						  "FROM toast_index", BTREE_AM_OID);
 	appendPQExpBufferStr(&sql,
 						 "\n) AS combined_records "
 						 "ORDER BY relpages DESC NULLS FIRST, oid");
@@ -2163,8 +2207,9 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 	{
 		int			pattern_id = -1;
 		bool		is_heap = false;
-		bool		is_btree PG_USED_FOR_ASSERTS_ONLY = false;
+		bool		is_index PG_USED_FOR_ASSERTS_ONLY = false;
 		Oid			oid = InvalidOid;
+		Oid			amoid = InvalidOid;
 		const char *nspname = NULL;
 		const char *relname = NULL;
 		int			relpages = 0;
@@ -2174,15 +2219,17 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 		if (!PQgetisnull(res, i, 1))
 			is_heap = (PQgetvalue(res, i, 1)[0] == 't');
 		if (!PQgetisnull(res, i, 2))
-			is_btree = (PQgetvalue(res, i, 2)[0] == 't');
+			is_index = (PQgetvalue(res, i, 2)[0] == 't');
 		if (!PQgetisnull(res, i, 3))
 			oid = atooid(PQgetvalue(res, i, 3));
 		if (!PQgetisnull(res, i, 4))
-			nspname = PQgetvalue(res, i, 4);
+			amoid = atooid(PQgetvalue(res, i, 4));
 		if (!PQgetisnull(res, i, 5))
-			relname = PQgetvalue(res, i, 5);
+			nspname = PQgetvalue(res, i, 5);
 		if (!PQgetisnull(res, i, 6))
-			relpages = atoi(PQgetvalue(res, i, 6));
+			relname = PQgetvalue(res, i, 6);
+		if (!PQgetisnull(res, i, 7))
+			relpages = atoi(PQgetvalue(res, i, 7));
 
 		if (pattern_id >= 0)
 		{
@@ -2204,10 +2251,11 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			RelationInfo *rel = (RelationInfo *) pg_malloc0(sizeof(RelationInfo));
 
 			Assert(OidIsValid(oid));
-			Assert((is_heap && !is_btree) || (is_btree && !is_heap));
+			Assert((is_heap && !is_index) || (is_index && !is_heap));
 
 			rel->datinfo = dat;
 			rel->reloid = oid;
+			rel->amoid = amoid;
 			rel->is_heap = is_heap;
 			rel->nspname = pstrdup(nspname);
 			rel->relname = pstrdup(relname);
@@ -2217,7 +2265,7 @@ compile_relation_list_one_db(PGconn *conn, SimplePtrList *relations,
 			{
 				/*
 				 * We apply --startblock and --endblock to heap tables, but
-				 * not btree indexes, and for progress purposes we need to
+				 * not supported indexes, and for progress purposes we need to
 				 * track how many blocks we expect to check.
 				 */
 				if (opts.endblock >= 0 && rel->blocks_to_check > opts.endblock)
diff --git a/src/bin/pg_amcheck/t/002_nonesuch.pl b/src/bin/pg_amcheck/t/002_nonesuch.pl
index 67d700ea07a..d4cc0664f3b 100644
--- a/src/bin/pg_amcheck/t/002_nonesuch.pl
+++ b/src/bin/pg_amcheck/t/002_nonesuch.pl
@@ -272,8 +272,8 @@ $node->command_checks_all(
 	[
 		qr/pg_amcheck: warning: no heap tables to check matching "no_such_table"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no_such_index"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "no\*such\*index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no_such_index"/,
+		qr/pg_amcheck: warning: no indexes to check matching "no\*such\*index"/,
 		qr/pg_amcheck: warning: no relations to check matching "no_such_relation"/,
 		qr/pg_amcheck: warning: no relations to check matching "no\*such\*relation"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "no\*such\*table"/,
@@ -350,8 +350,8 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: no heap tables to check matching "template1\.public\.foo"/,
 		qr/pg_amcheck: warning: no heap tables to check matching "another_db\.public\.foo"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "template1\.public\.foo_idx"/,
-		qr/pg_amcheck: warning: no btree indexes to check matching "another_db\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "template1\.public\.foo_idx"/,
+		qr/pg_amcheck: warning: no indexes to check matching "another_db\.public\.foo_idx"/,
 		qr/pg_amcheck: warning: no connectable databases to check matching "no_such_database\.public\.foo_idx"/,
 		qr/pg_amcheck: error: no relations to check/,
 	],
diff --git a/src/bin/pg_amcheck/t/003_check.pl b/src/bin/pg_amcheck/t/003_check.pl
index 2b57c4dbac1..0aa66b24258 100644
--- a/src/bin/pg_amcheck/t/003_check.pl
+++ b/src/bin/pg_amcheck/t/003_check.pl
@@ -185,7 +185,7 @@ for my $dbname (qw(db1 db2 db3))
 	# schemas.  The schemas are all identical to start, but
 	# we will corrupt them differently later.
 	#
-	for my $schema (qw(s1 s2 s3 s4 s5))
+	for my $schema (qw(s1 s2 s3 s4 s5 s6))
 	{
 		$node->safe_psql(
 			$dbname, qq(
@@ -291,22 +291,24 @@ plan_to_corrupt_first_page('db1', 's3.t2_btree');
 # Corrupt toast table, partitions, and materialized views in schema "s4"
 plan_to_remove_toast_file('db1', 's4.t2');
 
-# Corrupt all other object types in schema "s5".  We don't have amcheck support
+# Corrupt GiST index in schema "s5"
+plan_to_remove_relation_file('db1', 's5.t1_gist');
+plan_to_corrupt_first_page('db1', 's5.t2_gist');
+
+# Corrupt all other object types in schema "s6".  We don't have amcheck support
 # for these types, but we check that their corruption does not trigger any
 # errors in pg_amcheck
-plan_to_remove_relation_file('db1', 's5.seq1');
-plan_to_remove_relation_file('db1', 's5.t1_hash');
-plan_to_remove_relation_file('db1', 's5.t1_gist');
-plan_to_remove_relation_file('db1', 's5.t1_gin');
-plan_to_remove_relation_file('db1', 's5.t1_brin');
-plan_to_remove_relation_file('db1', 's5.t1_spgist');
+plan_to_remove_relation_file('db1', 's6.seq1');
+plan_to_remove_relation_file('db1', 's6.t1_hash');
+plan_to_remove_relation_file('db1', 's6.t1_gin');
+plan_to_remove_relation_file('db1', 's6.t1_brin');
+plan_to_remove_relation_file('db1', 's6.t1_spgist');
 
-plan_to_corrupt_first_page('db1', 's5.seq2');
-plan_to_corrupt_first_page('db1', 's5.t2_hash');
-plan_to_corrupt_first_page('db1', 's5.t2_gist');
-plan_to_corrupt_first_page('db1', 's5.t2_gin');
-plan_to_corrupt_first_page('db1', 's5.t2_brin');
-plan_to_corrupt_first_page('db1', 's5.t2_spgist');
+plan_to_corrupt_first_page('db1', 's6.seq2');
+plan_to_corrupt_first_page('db1', 's6.t2_hash');
+plan_to_corrupt_first_page('db1', 's6.t2_gin');
+plan_to_corrupt_first_page('db1', 's6.t2_brin');
+plan_to_corrupt_first_page('db1', 's6.t2_spgist');
 
 
 # Database 'db2' corruptions
@@ -437,10 +439,22 @@ $node->command_checks_all(
 	[$no_output_re],
 	'pg_amcheck in schema s4 excluding toast reports no corruption');
 
-# Check that no corruption is reported in schema db1.s5
-$node->command_checks_all([ @cmd, '-s', 's5', 'db1' ],
+# In schema db1.s5 we should see GiST corruption messages on stdout, and
+# nothing on stderr.
+#
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	2,
+	[
+		$missing_file_re, $line_pointer_corruption_re,
+	],
+	[$no_output_re],
+	'pg_amcheck schema s5 reports GiST index errors');
+
+# Check that no corruption is reported in schema db1.s6
+$node->command_checks_all([ @cmd, '-s', 's6', 'db1' ],
 	0, [$no_output_re], [$no_output_re],
-	'pg_amcheck over schema s5 reports no corruption');
+	'pg_amcheck over schema s6 reports no corruption');
 
 # In schema db1.s1, only indexes are corrupt.  Verify that when we exclude
 # the indexes, no corruption is reported about the schema.
@@ -551,7 +565,7 @@ $node->command_checks_all(
 	'pg_amcheck excluding all corrupt schemas with --checkunique option');
 
 #
-# Smoke test for checkunique option for not supported versions.
+# Smoke test for checkunique option and GiST indexes for not supported versions.
 #
 $node->safe_psql(
 	'db3', q(
@@ -567,4 +581,19 @@ $node->command_checks_all(
 		qr/pg_amcheck: warning: option --checkunique is not supported by amcheck version 1.3/
 	],
 	'pg_amcheck smoke test --checkunique');
+
+$node->safe_psql(
+	'db1', q(
+		DROP EXTENSION amcheck;
+		CREATE EXTENSION amcheck WITH SCHEMA amcheck_schema VERSION '1.3' ;
+));
+
+$node->command_checks_all(
+	[ @cmd, '-s', 's5', 'db1' ],
+	0,
+	[$no_output_re],
+	[
+		qr/pg_amcheck: warning: GiST verification is not supported by installed amcheck version/
+	],
+	'pg_amcheck smoke test --checkunique');
 done_testing();
-- 
2.34.1

From 22d9ee1315c2de44bba228d3feefed1e016d6e57 Mon Sep 17 00:00:00 2001
From: "Andrey M. Borodin" <x4mmm@flight.local>
Date: Sat, 23 Jul 2022 14:17:44 +0500
Subject: [PATCH v34 3/6] Add gist_index_check() function to verify GiST index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This function traverses GiST with a depth-fisrt search and checks
that all downlink tuples are included into parent tuple keyspace.
This traverse takes lock of any page until some discapency found.
To re-check suspicious pair of parent and child tuples it aqcuires
locks on both parent and child pages in the same order as page
split does.

Author: Andrey Borodin <amborodin@acm.org>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql   |  14 +
 contrib/amcheck/amcheck.control         |   2 +-
 contrib/amcheck/expected/check_gist.out | 145 +++++
 contrib/amcheck/meson.build             |   3 +
 contrib/amcheck/sql/check_gist.sql      |  62 +++
 contrib/amcheck/verify_gist.c           | 687 ++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml               |  19 +
 8 files changed, 935 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gist.out
 create mode 100644 contrib/amcheck/sql/check_gist.sql
 create mode 100644 contrib/amcheck/verify_gist.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..952e458c53b 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gist.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gist check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..3fc72364180
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gist_index_check()
+--
+CREATE FUNCTION gist_index_check(index regclass, heapallindexed boolean)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gist_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gist_index_check(regclass, boolean) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gist.out b/contrib/amcheck/expected/check_gist.out
new file mode 100644
index 00000000000..cbc3e27e679
--- /dev/null
+++ b/contrib/amcheck/expected/check_gist.out
@@ -0,0 +1,145 @@
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', false);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx1', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+SELECT gist_index_check('gist_check_idx2', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gist_check;
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+ attstorage 
+------------
+ x
+(1 row)
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
+ gist_index_check 
+------------------
+ 
+(1 row)
+
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 6a1ba5d7619..5ab83ca7778 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'verify_common.c',
+  'verify_gist.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gist',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gist.sql b/contrib/amcheck/sql/check_gist.sql
new file mode 100644
index 00000000000..37966423b8b
--- /dev/null
+++ b/contrib/amcheck/sql/check_gist.sql
@@ -0,0 +1,62 @@
+
+SELECT setseed(1);
+
+-- Test that index built with bulk load is correct
+CREATE TABLE gist_check AS SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+CREATE INDEX gist_check_idx1 ON gist_check USING gist(c);
+CREATE INDEX gist_check_idx2 ON gist_check USING gist(c) INCLUDE(p);
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after inserts
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+-- Test that index is correct after vacuuming
+DELETE FROM gist_check WHERE c[1] < 5000; -- delete clustered data
+DELETE FROM gist_check WHERE c[1]::int % 2 = 0; -- delete scattered data
+
+-- We need two passes through the index and one global vacuum to actually
+-- reuse page
+VACUUM gist_check;
+VACUUM;
+
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+
+
+-- Test that index is correct after reusing pages
+INSERT INTO gist_check SELECT point(random(),s) c, random() p FROM generate_series(1,10000) s;
+SELECT gist_index_check('gist_check_idx1', false);
+SELECT gist_index_check('gist_check_idx2', false);
+SELECT gist_index_check('gist_check_idx1', true);
+SELECT gist_index_check('gist_check_idx2', true);
+-- cleanup
+DROP TABLE gist_check;
+
+--
+-- Similar to BUG #15597
+--
+CREATE TABLE toast_bug(c point,buggy text);
+ALTER TABLE toast_bug ALTER COLUMN buggy SET STORAGE extended;
+CREATE INDEX toasty ON toast_bug USING gist(c) INCLUDE(buggy);
+
+-- pg_attribute entry for toasty.buggy (the index) will have plain storage:
+UPDATE pg_attribute SET attstorage = 'p'
+WHERE attrelid = 'toasty'::regclass AND attname = 'buggy';
+
+-- Whereas pg_attribute entry for toast_bug.buggy (the table) still has extended storage:
+SELECT attstorage FROM pg_attribute
+WHERE attrelid = 'toast_bug'::regclass AND attname = 'buggy';
+
+-- Insert compressible heap tuple (comfortably exceeds TOAST_TUPLE_THRESHOLD):
+INSERT INTO toast_bug SELECT point(0,0), repeat('a', 2200);
+-- Should not get false positive report of corruption:
+SELECT gist_index_check('toasty', true);
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gist.c b/contrib/amcheck/verify_gist.c
new file mode 100644
index 00000000000..477150ac802
--- /dev/null
+++ b/contrib/amcheck/verify_gist.c
@@ -0,0 +1,687 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gist.c
+ *		Verifies the integrity of GiST indexes based on invariants.
+ *
+ * Verification checks that all paths in GiST graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gist_private.h"
+#include "access/tableam.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "common/pg_prng.h"
+#include "lib/bloomfilter.h"
+#include "verify_common.h"
+#include "utils/memutils.h"
+
+
+/*
+ * GistScanItem represents one item of depth-first scan of GiST index.
+ */
+typedef struct GistScanItem
+{
+	int			depth;
+
+	/* Referenced block number to check next */
+	BlockNumber blkno;
+
+	/*
+	 * Correctess of this parent tuple will be checked against contents of
+	 * referenced page. This tuple will be NULL for root block.
+	 */
+	IndexTuple	parenttup;
+
+	/*
+	 * LSN to hande concurrent scan of the page. It's necessary to avoid
+	 * missing some subtrees from page, that was split just before we read it.
+	 */
+	XLogRecPtr	parentlsn;
+
+	/*
+	 * Reference to parent page for re-locking in case of found parent-child
+	 * tuple discrepencies.
+	 */
+	BlockNumber parentblk;
+
+	/* Pointer to a next stack item. */
+	struct GistScanItem *next;
+}			GistScanItem;
+
+typedef struct GistCheckState
+{
+	/* GiST state */
+	GISTSTATE  *state;
+	/* Bloom filter fingerprints index tuples */
+	bloom_filter *filter;
+
+	Snapshot	snapshot;
+	Relation	rel;
+	Relation	heaprel;
+
+	/* Debug counter for reporting percentage of work already done */
+	int64		heaptuplespresent;
+
+	/* progress reporting stuff */
+	BlockNumber totalblocks;
+	BlockNumber reportedblocks;
+	BlockNumber scannedblocks;
+	BlockNumber deltablocks;
+
+	int			leafdepth;
+}			GistCheckState;
+
+PG_FUNCTION_INFO_V1(gist_index_check);
+
+static void giststate_init_heapallindexed(Relation rel, GistCheckState * result);
+static void gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+											   void *callback_state, bool readonly);
+static void gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+							Page page, bool heapallindexed,
+							BufferAccessStrategy strategy);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gist_refind_parent(Relation rel, BlockNumber parentblkno,
+									 BlockNumber childblkno,
+									 BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block,
+								   Page page, OffsetNumber offset);
+static void gist_tuple_present_callback(Relation index, ItemPointer tid,
+										Datum *values, bool *isnull,
+										bool tupleIsAlive, void *checkstate);
+static IndexTuple gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+										  Datum *attdata, bool *isnull, ItemPointerData tid);
+
+/*
+ * gist_index_check(index regclass)
+ *
+ * Verify integrity of GiST index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gist_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+	bool		heapallindexed = PG_GETARG_BOOL(1);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIST_AM_OID,
+									gist_check_parent_keys_consistency,
+									AccessShareLock,
+									&heapallindexed);
+
+	PG_RETURN_VOID();
+}
+
+/*
+* Initaliaze GIST state filed needed to perform.
+* This initialized bloom filter and snapshot.
+*/
+static void
+giststate_init_heapallindexed(Relation rel, GistCheckState * result)
+{
+	int64		total_pages;
+	int64		total_elems;
+	uint64		seed;
+
+	/*
+	 * Size Bloom filter based on estimated number of tuples in index. This
+	 * logic is similar to B-tree, see verify_btree.c .
+	 */
+	total_pages = result->totalblocks;
+	total_elems = Max(total_pages * (MaxOffsetNumber / 5),
+					  (int64) rel->rd_rel->reltuples);
+	seed = pg_prng_uint64(&pg_global_prng_state);
+	result->filter = bloom_create(total_elems, maintenance_work_mem, seed);
+
+	result->snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+
+	/*
+	 * GetTransactionSnapshot() always acquires a new MVCC snapshot in READ
+	 * COMMITTED mode.  A new snapshot is guaranteed to have all the entries
+	 * it requires in the index.
+	 *
+	 * We must defend against the possibility that an old xact snapshot was
+	 * returned at higher isolation levels when that snapshot is not safe for
+	 * index scans of the target index.  This is possible when the snapshot
+	 * sees tuples that are before the index's indcheckxmin horizon.  Throwing
+	 * an error here should be very rare.  It doesn't seem worth using a
+	 * secondary snapshot to avoid this.
+	 */
+	if (IsolationUsesXactSnapshot() && rel->rd_index->indcheckxmin &&
+		!TransactionIdPrecedes(HeapTupleHeaderGetXmin(rel->rd_indextuple->t_data),
+							   result->snapshot->xmin))
+		ereport(ERROR,
+				(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
+				 errmsg("index \"%s\" cannot be verified using transaction snapshot",
+						RelationGetRelationName(rel))));
+}
+
+/*
+ * Main entry point for GiST check.
+ *
+ * This function verifies that tuples of internal pages cover all
+ * the key space of each tuple on leaf page.  To do this we invoke
+ * gist_check_internal_page() for every internal page.
+ *
+ * This check allocates memory context and scans through
+ * GiST graph. This scan is performed in a depth-first search using a stack of
+ * GistScanItem-s. Initially this stack contains only root block number. On
+ * each iteration top block numbmer is replcaed by referenced block numbers.
+ *
+ *
+ * gist_check_internal_page() in it's turn takes every tuple and tries to
+ * adjust it by tuples on referenced child page.  Parent gist tuple should
+ * never require any adjustments.
+ */
+static void
+gist_check_parent_keys_consistency(Relation rel, Relation heaprel,
+								   void *callback_state, bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GistScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GISTSTATE  *state;
+	bool		heapallindexed = *((bool *) callback_state);
+	GistCheckState *check_state = palloc0(sizeof(GistCheckState));
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	state = initGISTstate(rel);
+
+	check_state->state = state;
+	check_state->rel = rel;
+	check_state->heaprel = heaprel;
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	check_state->leafdepth = -1;
+
+	check_state->totalblocks = RelationGetNumberOfBlocks(rel);
+	/* report every 100 blocks or 5%, whichever is bigger */
+	check_state->deltablocks = Max(check_state->totalblocks / 20, 100);
+
+	if (heapallindexed)
+		giststate_init_heapallindexed(rel, check_state);
+
+	/* Start the scan at the root page */
+	stack = (GistScanItem *) palloc0(sizeof(GistScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIST_ROOT_BLKNO;
+
+	/*
+	 * This GiST scan is effectively "old" VACUUM version before commit
+	 * fe280694d which introduced physical order scanning.
+	 */
+
+	while (stack)
+	{
+		GistScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		XLogRecPtr	lsn;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Report progress */
+		if (check_state->scannedblocks > check_state->reportedblocks +
+			check_state->deltablocks)
+		{
+			elog(DEBUG1, "verified level %u blocks of approximately %u total",
+				 check_state->scannedblocks, check_state->totalblocks);
+			check_state->reportedblocks = check_state->scannedblocks;
+		}
+		check_state->scannedblocks++;
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIST_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (GistFollowRight(page) || stack->parentlsn < GistPageGetNSN(page))
+		{
+			/* split page detected, install right link to the stack */
+			GistScanItem *ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+
+			ptr->depth = stack->depth;
+			ptr->parenttup = CopyIndexTuple(stack->parenttup);
+			ptr->parentblk = stack->parentblk;
+			ptr->parentlsn = stack->parentlsn;
+			ptr->blkno = GistPageGetOpaque(page)->rightlink;
+			ptr->next = stack->next;
+			stack->next = ptr;
+		}
+
+		gist_check_page(check_state, stack, page, heapallindexed, strategy);
+
+		if (!GistPageIsLeaf(page))
+		{
+			OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+			for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				/* Internal page, so recurse to the child */
+				GistScanItem *ptr;
+				ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+				IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+				ptr = (GistScanItem *) palloc(sizeof(GistScanItem));
+				ptr->depth = stack->depth + 1;
+				ptr->parenttup = CopyIndexTuple(idxtuple);
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid));
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		LockBuffer(buffer, GIST_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	if (heapallindexed)
+	{
+		IndexInfo  *indexinfo = BuildIndexInfo(rel);
+		TableScanDesc scan;
+
+		scan = table_beginscan_strat(heaprel,	/* relation */
+									 check_state->snapshot, /* snapshot */
+									 0, /* number of keys */
+									 NULL,	/* scan key */
+									 true,	/* buffer access strategy OK */
+									 true); /* syncscan OK? */
+
+		/*
+		 * Scan will behave as the first scan of a CREATE INDEX CONCURRENTLY.
+		 */
+		indexinfo->ii_Concurrent = true;
+
+		indexinfo->ii_Unique = false;
+		indexinfo->ii_ExclusionOps = NULL;
+		indexinfo->ii_ExclusionProcs = NULL;
+		indexinfo->ii_ExclusionStrats = NULL;
+
+		elog(DEBUG1, "verifying that tuples from index \"%s\" are present in \"%s\"",
+			 RelationGetRelationName(rel),
+			 RelationGetRelationName(heaprel));
+
+		table_index_build_scan(heaprel, rel, indexinfo, true, false,
+							   gist_tuple_present_callback, (void *) check_state, scan);
+
+		ereport(DEBUG1,
+				(errmsg_internal("finished verifying presence of " INT64_FORMAT " tuples from table \"%s\" with bitset %.2f%% set",
+								 check_state->heaptuplespresent,
+								 RelationGetRelationName(heaprel),
+								 100.0 * bloom_prop_bits_set(check_state->filter))));
+
+		UnregisterSnapshot(check_state->snapshot);
+		bloom_free(check_state->filter);
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+	pfree(check_state);
+}
+
+static void
+gist_check_page(GistCheckState * check_state, GistScanItem * stack,
+				Page page, bool heapallindexed, BufferAccessStrategy strategy)
+{
+	OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+
+	/* Check that the tree has the same height in all branches */
+	if (GistPageIsLeaf(page))
+	{
+		if (check_state->leafdepth == -1)
+			check_state->leafdepth = stack->depth;
+		else if (stack->depth != check_state->leafdepth)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+							RelationGetRelationName(check_state->rel), stack->blkno)));
+	}
+
+	/*
+	 * Check that each tuple looks valid, and is consistent with the downlink
+	 * we followed when we stepped on this page.
+	 */
+	for (OffsetNumber i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+	{
+		ItemId		iid = PageGetItemIdCareful(check_state->rel, stack->blkno, page, i);
+		IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+		IndexTuple  tmpTuple = NULL;
+
+		/*
+		 * Check that it's not a leftover invalid tuple from pre-9.1 See also
+		 * gistdoinsert() and gistbulkdelete() handling of such tuples. We do
+		 * consider it error here.
+		 */
+		if (GistTupleIsInvalid(idxtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("index \"%s\" contains an inner tuple marked as invalid, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i),
+					 errdetail("This is caused by an incomplete page split at crash recovery before upgrading to PostgreSQL 9.1."),
+					 errhint("Please REINDEX it.")));
+
+		if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+							RelationGetRelationName(check_state->rel), stack->blkno, i)));
+
+		/*
+		 * Check if this tuple is consistent with the downlink in the parent.
+		 */
+		if (stack->parenttup)
+			tmpTuple = gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state);
+
+		if (tmpTuple)
+		{
+			/*
+			 * There was a discrepancy between parent and child tuples. We
+			 * need to verify it is not a result of concurrent call of
+			 * gistplacetopage(). So, lock parent and try to find downlink for
+			 * current page. It may be missing due to concurrent page split,
+			 * this is OK.
+			 *
+			 * Note that when we aquire parent tuple now we hold lock for both
+			 * parent and child buffers. Thus parent tuple must include
+			 * keyspace of the child.
+			 */
+
+			pfree(tmpTuple);
+			pfree(stack->parenttup);
+			stack->parenttup = gist_refind_parent(check_state->rel, stack->parentblk,
+												  stack->blkno, strategy);
+
+			/* We found it - make a final check before failing */
+			if (!stack->parenttup)
+				elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+					 stack->blkno, stack->parentblk);
+			else if (gistgetadjusted(check_state->rel, stack->parenttup, idxtuple, check_state->state))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+								RelationGetRelationName(check_state->rel), stack->blkno, i)));
+			else
+			{
+				/*
+				 * But now it is properly adjusted - nothing to do here.
+				 */
+			}
+		}
+
+		if (GistPageIsLeaf(page))
+		{
+			if (heapallindexed)
+				bloom_add_element(check_state->filter,
+								  (unsigned char *) idxtuple,
+								  IndexTupleSize(idxtuple));
+		}
+		else
+		{
+			OffsetNumber off = ItemPointerGetOffsetNumber(&(idxtuple->t_tid));
+
+			if (off != 0xffff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has on page %u offset %u has item id not pointing to 0xffff, but %hu",
+								RelationGetRelationName(check_state->rel), stack->blkno, i, off)));
+		}
+	}
+}
+
+/*
+ * gistFormNormalizedTuple - analogue to gistFormTuple, but performs deTOASTing
+ * of all included data (for covering indexes). While we do not expected
+ * toasted attributes in normal index, this can happen as a result of
+ * intervention into system catalog. Detoasting of key attributes is expected
+ * to be done by opclass decompression methods, if indexed type might be
+ * toasted.
+ */
+static IndexTuple
+gistFormNormalizedTuple(GISTSTATE *giststate, Relation r,
+						Datum *attdata, bool *isnull, ItemPointerData tid)
+{
+	Datum		compatt[INDEX_MAX_KEYS];
+	IndexTuple	res;
+
+	gistCompressValues(giststate, r, attdata, isnull, true, compatt);
+
+	for (int i = 0; i < r->rd_att->natts; i++)
+	{
+		Form_pg_attribute att;
+
+		att = TupleDescAttr(giststate->leafTupdesc, i);
+		if (att->attbyval || att->attlen != -1 || isnull[i])
+			continue;
+
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(compatt[i])))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("external varlena datum in tuple that references heap row (%u,%u) in index \"%s\"",
+							ItemPointerGetBlockNumber(&tid),
+							ItemPointerGetOffsetNumber(&tid),
+							RelationGetRelationName(r))));
+		if (VARATT_IS_COMPRESSED(DatumGetPointer(compatt[i])))
+		{
+			/* Datum old = compatt[i]; */
+			/* Key attributes must never be compressed */
+			if (i < IndexRelationGetNumberOfKeyAttributes(r))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("compressed varlena datum in tuple key that references heap row (%u,%u) in index \"%s\"",
+								ItemPointerGetBlockNumber(&tid),
+								ItemPointerGetOffsetNumber(&tid),
+								RelationGetRelationName(r))));
+
+			compatt[i] = PointerGetDatum(PG_DETOAST_DATUM(compatt[i]));
+			/* pfree(DatumGetPointer(old)); // TODO: this fails. Why? */
+		}
+	}
+
+	res = index_form_tuple(giststate->leafTupdesc, compatt, isnull);
+
+	/*
+	 * The offset number on tuples on internal pages is unused. For historical
+	 * reasons, it is set to 0xffff.
+	 */
+	ItemPointerSetOffsetNumber(&(res->t_tid), 0xffff);
+	return res;
+}
+
+static void
+gist_tuple_present_callback(Relation index, ItemPointer tid, Datum *values,
+							bool *isnull, bool tupleIsAlive, void *checkstate)
+{
+	GistCheckState *state = (GistCheckState *) checkstate;
+	IndexTuple	itup = gistFormNormalizedTuple(state->state, index, values, isnull, *tid);
+
+	itup->t_tid = *tid;
+	/* Probe Bloom filter -- tuple should be present */
+	if (bloom_lacks_element(state->filter, (unsigned char *) itup,
+							IndexTupleSize(itup)))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg("heap tuple (%u,%u) from table \"%s\" lacks matching index tuple within index \"%s\"",
+						ItemPointerGetBlockNumber(&(itup->t_tid)),
+						ItemPointerGetOffsetNumber(&(itup->t_tid)),
+						RelationGetRelationName(state->heaprel),
+						RelationGetRelationName(state->rel))));
+
+	state->heaptuplespresent++;
+
+	pfree(itup);
+}
+
+/*
+ * check_index_page - verification of basic invariants about GiST page data
+ * This function does no any tuple analysis.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	gistcheckpage(rel, buffer);
+
+	if (GistPageGetOpaque(page)->gist_page_id != GIST_PAGE_ID)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has corrupted page %d",
+						RelationGetRelationName(rel), blockNo)));
+
+	if (GistPageIsDeleted(page))
+	{
+		if (!GistPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gist_refind_parent(Relation rel,
+				   BlockNumber parentblkno, BlockNumber childblkno,
+				   BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIST_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GistPageIsLeaf(parentpage))
+	{
+		/*
+		 * Currently GiST never deletes internal pages, thus they can never
+		 * become leaf.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" internal page %d became leaf",
+						RelationGetRelationName(rel), parentblkno)));
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (OffsetNumber o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/*
+			 * Found it! Make copy and return it while both parent and child
+			 * pages are locked. This guaranties that at this particular
+			 * moment tuples must be coherent to each other.
+			 */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GISTPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED, since gist
+	 * never uses either.  Verify that line pointer has storage, too, since
+	 * even LP_DEAD items should.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..6eb526c6bb7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,25 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gist_index_check(index regclass, heapallindexed boolean) returns void</function>
+     <indexterm>
+      <primary>gist_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gist_index_check</function> tests that its target GiST
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
   <tip>
    <para>
-- 
2.34.1

From 4bc20e477d7d55373a9cddfedc5ed22b6f96de3d Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 3 Dec 2024 15:02:47 +0000
Subject: [PATCH v34 6/6] Fix wording in GIN README.

---
 src/backend/access/gin/README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/gin/README b/src/backend/access/gin/README
index b0807316212..742bcbad499 100644
--- a/src/backend/access/gin/README
+++ b/src/backend/access/gin/README
@@ -237,10 +237,10 @@ GIN packs keys and downlinks into tuples in a different way.
 
 P_i is grouped with K_{i+1}.  -Inf key is not needed.
 
-There are couple of additional notes regarding K_{n+1} key.
-1) In entry tree rightmost page, a key coupled with P_n doesn't really matter.
+There are a couple of additional notes regarding K_{n+1} key.
+1) In the entry tree on the rightmost page, a key coupled with P_n doesn't really matter.
 Highkey is assumed to be infinity.
-2) In posting tree, a key coupled with P_n always doesn't matter.  Highkey for
+2) In the posting tree, a key coupled with P_n always doesn't matter.  Highkey for
 non-rightmost pages is stored separately and accessed via
 GinDataPageGetRightBound().
 
-- 
2.34.1

From ba3d5cc709e9b1f0adef6616f77baba04a63f471 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Mon, 16 Dec 2024 10:49:43 +0000
Subject: [PATCH v35] Fix for gin_index_check.

Never explicitly check high key on rightmost page is entry tree.
Its value is not stored explicitly and is equal to infitity.
---
 contrib/amcheck/verify_gin.c | 43 ++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 2dc5fbba619..74783af54d4 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -163,6 +163,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 		Page		page;
 		OffsetNumber i,
 					maxoff;
+		BlockNumber rightlink;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -170,6 +171,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 									RBM_NORMAL, strategy);
 		LockBuffer(buffer, GIN_SHARE);
 		page = (Page) BufferGetPage(buffer);
+
 		Assert(GinPageIsData(page));
 
 		/* Check that the tree has the same height in all branches */
@@ -234,8 +236,8 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			 * Check that tuples in each page are properly ordered and
 			 * consistent with parent high key
 			 */
-			Assert(GinPageIsData(page));
 			maxoff = GinPageGetOpaque(page)->maxoff;
+			rightlink = GinPageGetOpaque(page)->rightlink;
 
 			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
 
@@ -273,7 +275,12 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			 */
 			bound = *GinDataPageGetRightBound(page);
 
-			if (stack->parentblk != InvalidBlockNumber &&
+			/*
+			 * Gin page right bound has sane value if only not a highkey on
+			 * rightmost page on level.
+			 */
+			if (ItemPointerIsValid(&stack->parentkey) &&
+				rightlink != InvalidBlockNumber &&
 				!ItemPointerEquals(&stack->parentkey, &bound))
 				ereport(ERROR,
 						(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -287,11 +294,12 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 
 			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
 			{
+				GinPostingTreeScanItem *ptr;
 				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
 
 				/* ItemPointerGetOffsetNumber expects a valid pointer */
 				if (!(i == maxoff &&
-					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					  rightlink == InvalidBlockNumber))
 					elog(DEBUG3, "key (%u, %u) -> %u",
 						 ItemPointerGetBlockNumber(&posting_item->key),
 						 ItemPointerGetOffsetNumber(&posting_item->key),
@@ -300,8 +308,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 					elog(DEBUG3, "key (%u, %u) -> %u",
 						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
 
-				if (i == maxoff &&
-					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 				{
 					/*
 					 * The rightmost item in the tree level has (0, 0) as the
@@ -340,19 +347,23 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 									RelationGetRelationName(rel),
 									stack->blkno, i)));
 
-				/* If this is an internal page, recurse into the child */
-				if (!GinPageIsLeaf(page))
-				{
-					GinPostingTreeScanItem *ptr;
+				/* This is an internal page, recurse into the child */
+				ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+				ptr->depth = stack->depth + 1;
 
-					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
-					ptr->depth = stack->depth + 1;
+				/*
+				 * Set rightmost parent key to invalid iterm pointer. Its
+				 * value is 'Infinity' and not explicitly stored.
+				 */
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
 					ptr->parentkey = posting_item->key;
-					ptr->parentblk = stack->blkno;
-					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
-					ptr->next = stack->next;
-					stack->next = ptr;
-				}
+
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+				ptr->next = stack->next;
+				stack->next = ptr;
 			}
 		}
 		LockBuffer(buffer, GIN_UNLOCK);
-- 
2.34.1

From 7c472ae3a64e4576e1779e0636c0016e89656829 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 26 Nov 2024 05:32:27 +0000
Subject: [PATCH v36 1/8] A tiny nitpicky tweak to beautify the Amcheck
 interiors.

The heaptuplespresent field in BtreeCheckState was not previously
adequately documented. To clarify the meaning of this field, the comment was changed.
---
 contrib/amcheck/verify_nbtree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index aac8c74f546..7543be17552 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -124,7 +124,7 @@ typedef struct BtreeCheckState
 
 	/* Bloom filter fingerprints B-Tree index */
 	bloom_filter *filter;
-	/* Debug counter */
+	/* Debug counter for reporting percentage of work already done */
 	int64		heaptuplespresent;
 } BtreeCheckState;
 
-- 
2.39.3 (Apple Git-145)

From 2e9b9d7d105b4f8279a6c953d832616b8b256c8d Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 09:18:04 -0800
Subject: [PATCH v36 2/8] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 61d7eaf2305..67a4ac8518d 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2025, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'verify_common.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..c8ed685ba42
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_common.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_common.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 7543be17552..9dc76f0e5d4 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.39.3 (Apple Git-145)

From dfab1f7b014e3338143872ef839c18020c6a8525 Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 09:27:00 -0800
Subject: [PATCH v36 3/8] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |  14 +
 contrib/amcheck/amcheck.control        |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   3 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 774 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  20 +
 8 files changed, 920 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..1b7a63cbaa4 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gin check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..445c48ccb7d
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 67a4ac8518d..b33e8c9b062 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'verify_common.c',
+  'verify_gin.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..2dc5fbba619
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,774 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[MAXPGPATH];
+
+			ItemPointerSetMin(&minItem);
+
+			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			Assert(GinPageIsData(page));
+			maxoff = GinPageGetOpaque(page)->maxoff;
+
+			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				/* ItemPointerGetOffsetNumber expects a valid pointer */
+				if (!(i == maxoff &&
+					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 ItemPointerGetBlockNumber(&posting_item->key),
+						 ItemPointerGetOffsetNumber(&posting_item->key),
+						 BlockIdGetBlockNumber(&posting_item->child_blkno));
+				else
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+		BlockNumber rightlink;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+		rightlink = GinPageGetOpaque(page)->rightlink;
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		elog(DEBUG3, "processing entry tree page at blk %u, maxoff: %u", stack->blkno, maxoff);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected for blk: %u, parent blk: %u", stack->blkno, stack->parentblk);
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/*
+			 * First block is metadata, skip order check. Also, never check
+			 * for high key on rightmost page, as this key is not really
+			 * stored explicitly.
+			 */
+			if (i != FirstOffsetNumber && stack->blkno != GIN_ROOT_BLKNO &&
+				!(i == maxoff && rightlink == InvalidBlockNumber))
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						 * Check if it is properly adjusted. If succeed,
+						 * procced to the next key.
+						 */
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index 3af065615bc..08290c5a448 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,26 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
   </variablelist>
   <tip>
    <para>
-- 
2.39.3 (Apple Git-145)

From 16c96fa6df59f8419ea935e77448fa3db3ef8efc Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 3 Dec 2024 15:02:47 +0000
Subject: [PATCH v36 4/8] Fix wording in GIN README.

---
 src/backend/access/gin/README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/gin/README b/src/backend/access/gin/README
index b0807316212..742bcbad499 100644
--- a/src/backend/access/gin/README
+++ b/src/backend/access/gin/README
@@ -237,10 +237,10 @@ GIN packs keys and downlinks into tuples in a different way.
 
 P_i is grouped with K_{i+1}.  -Inf key is not needed.
 
-There are couple of additional notes regarding K_{n+1} key.
-1) In entry tree rightmost page, a key coupled with P_n doesn't really matter.
+There are a couple of additional notes regarding K_{n+1} key.
+1) In the entry tree on the rightmost page, a key coupled with P_n doesn't really matter.
 Highkey is assumed to be infinity.
-2) In posting tree, a key coupled with P_n always doesn't matter.  Highkey for
+2) In the posting tree, a key coupled with P_n always doesn't matter.  Highkey for
 non-rightmost pages is stored separately and accessed via
 GinDataPageGetRightBound().
 
-- 
2.39.3 (Apple Git-145)

From 330ad2f0fa34e6f2dffe19afa340cd3da2261920 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Mon, 16 Dec 2024 10:49:43 +0000
Subject: [PATCH v36 5/8] Fix for gin_index_check.

Never explicitly check high key on rightmost page is entry tree.
Its value is not stored explicitly and is equal to infitity.
---
 contrib/amcheck/verify_gin.c | 43 ++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 2dc5fbba619..74783af54d4 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -163,6 +163,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 		Page		page;
 		OffsetNumber i,
 					maxoff;
+		BlockNumber rightlink;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -170,6 +171,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 									RBM_NORMAL, strategy);
 		LockBuffer(buffer, GIN_SHARE);
 		page = (Page) BufferGetPage(buffer);
+
 		Assert(GinPageIsData(page));
 
 		/* Check that the tree has the same height in all branches */
@@ -234,8 +236,8 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			 * Check that tuples in each page are properly ordered and
 			 * consistent with parent high key
 			 */
-			Assert(GinPageIsData(page));
 			maxoff = GinPageGetOpaque(page)->maxoff;
+			rightlink = GinPageGetOpaque(page)->rightlink;
 
 			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
 
@@ -273,7 +275,12 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			 */
 			bound = *GinDataPageGetRightBound(page);
 
-			if (stack->parentblk != InvalidBlockNumber &&
+			/*
+			 * Gin page right bound has sane value if only not a highkey on
+			 * rightmost page on level.
+			 */
+			if (ItemPointerIsValid(&stack->parentkey) &&
+				rightlink != InvalidBlockNumber &&
 				!ItemPointerEquals(&stack->parentkey, &bound))
 				ereport(ERROR,
 						(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -287,11 +294,12 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 
 			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
 			{
+				GinPostingTreeScanItem *ptr;
 				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
 
 				/* ItemPointerGetOffsetNumber expects a valid pointer */
 				if (!(i == maxoff &&
-					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					  rightlink == InvalidBlockNumber))
 					elog(DEBUG3, "key (%u, %u) -> %u",
 						 ItemPointerGetBlockNumber(&posting_item->key),
 						 ItemPointerGetOffsetNumber(&posting_item->key),
@@ -300,8 +308,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 					elog(DEBUG3, "key (%u, %u) -> %u",
 						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
 
-				if (i == maxoff &&
-					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 				{
 					/*
 					 * The rightmost item in the tree level has (0, 0) as the
@@ -340,19 +347,23 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 									RelationGetRelationName(rel),
 									stack->blkno, i)));
 
-				/* If this is an internal page, recurse into the child */
-				if (!GinPageIsLeaf(page))
-				{
-					GinPostingTreeScanItem *ptr;
+				/* This is an internal page, recurse into the child */
+				ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+				ptr->depth = stack->depth + 1;
 
-					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
-					ptr->depth = stack->depth + 1;
+				/*
+				 * Set rightmost parent key to invalid iterm pointer. Its
+				 * value is 'Infinity' and not explicitly stored.
+				 */
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
 					ptr->parentkey = posting_item->key;
-					ptr->parentblk = stack->blkno;
-					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
-					ptr->next = stack->next;
-					stack->next = ptr;
-				}
+
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+				ptr->next = stack->next;
+				stack->next = ptr;
 			}
 		}
 		LockBuffer(buffer, GIN_UNLOCK);
-- 
2.39.3 (Apple Git-145)

From 010d4cf5502695d8f745423ad5769b34192389ff Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 09:40:37 -0800
Subject: [PATCH v36 6/8] Add gin index checking test for jsonb data

Extend the previously committed test of gin index checking to also
include a table using jsonb_path_ops.
---
 contrib/amcheck/expected/check_gin.out | 14 ++++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 12 ++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index bbcde80e627..93147de0ef1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -62,3 +62,17 @@ SELECT gin_index_check('gin_check_text_array_idx');
 
 -- cleanup
 DROP TABLE gin_check_text_array;
+-- Test GIN over jsonb
+CREATE TABLE "gin_check_jsonb"("j" jsonb);
+INSERT INTO gin_check_jsonb values ('{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
+INSERT INTO gin_check_jsonb values ('[[14,2,3]]');
+INSERT INTO gin_check_jsonb values ('[1,[14,2,3]]');
+CREATE INDEX "gin_check_jsonb_idx" on gin_check_jsonb USING GIN("j" jsonb_path_ops);
+SELECT gin_index_check('gin_check_jsonb_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_jsonb;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index bbd9b9f8281..92ddbbc7a89 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -38,3 +38,15 @@ SELECT gin_index_check('gin_check_text_array_idx');
 
 -- cleanup
 DROP TABLE gin_check_text_array;
+
+-- Test GIN over jsonb
+CREATE TABLE "gin_check_jsonb"("j" jsonb);
+INSERT INTO gin_check_jsonb values ('{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
+INSERT INTO gin_check_jsonb values ('[[14,2,3]]');
+INSERT INTO gin_check_jsonb values ('[1,[14,2,3]]');
+CREATE INDEX "gin_check_jsonb_idx" on gin_check_jsonb USING GIN("j" jsonb_path_ops);
+
+SELECT gin_index_check('gin_check_jsonb_idx');
+
+-- cleanup
+DROP TABLE gin_check_jsonb;
-- 
2.39.3 (Apple Git-145)

From 1e9dbdf291f3b81d7ec702fe262b41933498257b Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 12:10:26 -0800
Subject: [PATCH v36 7/8] Add gin to the create index concurrently tap tests

These tests are already checking btree, and can cheaply be extended
to also check gin, so do that.
---
 contrib/amcheck/t/002_cic.pl     | 10 +++++---
 contrib/amcheck/t/003_cic_2pc.pl | 40 ++++++++++++++++++++++++++------
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
index 0b6a5a9e464..6a0c4f61125 100644
--- a/contrib/amcheck/t/002_cic.pl
+++ b/contrib/amcheck/t/002_cic.pl
@@ -21,8 +21,9 @@ $node->append_conf('postgresql.conf',
 	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
 $node->start;
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
-$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 $node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i)));
+$node->safe_psql('postgres', q(CREATE INDEX ginidx ON tbl USING gin(j)));
 
 #
 # Stress CIC with pgbench.
@@ -40,13 +41,13 @@ $node->pgbench(
 	{
 		'002_pgbench_concurrent_transaction' => q(
 			BEGIN;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0, '{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
 			COMMIT;
 		  ),
 		'002_pgbench_concurrent_transaction_savepoints' => q(
 			BEGIN;
 			SAVEPOINT s1;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 			COMMIT;
 		  ),
 		'002_pgbench_concurrent_cic' => q(
@@ -54,7 +55,10 @@ $node->pgbench(
 			\if :gotlock
 				DROP INDEX CONCURRENTLY idx;
 				CREATE INDEX CONCURRENTLY idx ON tbl(i);
+				DROP INDEX CONCURRENTLY ginidx;
+				CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 				SELECT bt_index_check('idx',true);
+				SELECT gin_index_check('ginidx');
 				SELECT pg_advisory_unlock(42);
 			\endif
 		  )
diff --git a/contrib/amcheck/t/003_cic_2pc.pl b/contrib/amcheck/t/003_cic_2pc.pl
index 9134487f3b4..00a446a381f 100644
--- a/contrib/amcheck/t/003_cic_2pc.pl
+++ b/contrib/amcheck/t/003_cic_2pc.pl
@@ -25,7 +25,7 @@ $node->append_conf('postgresql.conf',
 	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
 $node->start;
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
-$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 
 
 #
@@ -41,7 +41,7 @@ my $main_h = $node->background_psql('postgres');
 $main_h->query_safe(
 	q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
 my $cic_h = $node->background_psql('postgres');
@@ -50,6 +50,7 @@ $cic_h->query_until(
 	qr/start/, q(
 \echo start
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $main_h->query_safe(
@@ -60,7 +61,7 @@ PREPARE TRANSACTION 'a';
 $main_h->query_safe(
 	q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'a';));
@@ -69,7 +70,7 @@ $main_h->query_safe(
 	q(
 PREPARE TRANSACTION 'b';
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '"mary had a little lamb"');
 ));
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'b';));
@@ -86,6 +87,9 @@ $cic_h->quit;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after overlapping 2PC');
 
+$result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
+is($result, '0', 'gin_index_check after overlapping 2PC');
+
 
 #
 # Server restart shall not change whether prepared xact blocks CIC
@@ -94,7 +98,7 @@ is($result, '0', 'bt_index_check after overlapping 2PC');
 $node->safe_psql(
 	'postgres', q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
 PREPARE TRANSACTION 'spans_restart';
 BEGIN;
 CREATE TABLE unused ();
@@ -108,12 +112,16 @@ $reindex_h->query_until(
 \echo start
 DROP INDEX CONCURRENTLY idx;
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
+DROP INDEX CONCURRENTLY ginidx;
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $node->safe_psql('postgres', "COMMIT PREPARED 'spans_restart'");
 $reindex_h->quit;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after 2PC and restart');
+$result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
+is($result, '0', 'gin_index_check after 2PC and restart');
 
 
 #
@@ -136,14 +144,14 @@ $node->pgbench(
 	{
 		'003_pgbench_concurrent_2pc' => q(
 			BEGIN;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0,'null');
 			PREPARE TRANSACTION 'c:client_id';
 			COMMIT PREPARED 'c:client_id';
 		  ),
 		'003_pgbench_concurrent_2pc_savepoint' => q(
 			BEGIN;
 			SAVEPOINT s1;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0,'[false, "jnvaba", -76, 7, {"_": [1]}, 9]');
 			PREPARE TRANSACTION 'c:client_id';
 			COMMIT PREPARED 'c:client_id';
 		  ),
@@ -163,7 +171,25 @@ $node->pgbench(
 				SELECT bt_index_check('idx',true);
 				SELECT pg_advisory_unlock(42);
 			\endif
+		  ),
+		'005_pgbench_concurrent_cic' => q(
+			SELECT pg_try_advisory_lock(42)::integer AS gotginlock \gset
+			\if :gotginlock
+				DROP INDEX CONCURRENTLY ginidx;
+				CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
+				SELECT gin_index_check('ginidx');
+				SELECT pg_advisory_unlock(42);
+			\endif
+		  ),
+		'006_pgbench_concurrent_ric' => q(
+			SELECT pg_try_advisory_lock(42)::integer AS gotginlock \gset
+			\if :gotginlock
+				REINDEX INDEX CONCURRENTLY ginidx;
+				SELECT gin_index_check('ginidx');
+				SELECT pg_advisory_unlock(42);
+			\endif
 		  )
+
 	});
 
 $node->stop;
-- 
2.39.3 (Apple Git-145)

From 40858417c7fe2cfef0609e2e30e6f910fe25276f Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 12:11:07 -0800
Subject: [PATCH v36 8/8] Stress test verify_gin() using pgbench

Add a tap test which inserts, updates, deletes, and checks in
parallel.  Like all pgbench based tap tests, this test contains race
conditions between the operations, so Your Mileage May Vary.  For
me, on my laptop, I got failures like:

	index "ginidx" has wrong tuple order on entry tree page

which I have not yet investigated.  The test is included here for
anybody interested in debugging this failure.
---
 contrib/amcheck/t/006_gin_concurrency.pl | 196 +++++++++++++++++++++++
 1 file changed, 196 insertions(+)
 create mode 100644 contrib/amcheck/t/006_gin_concurrency.pl

diff --git a/contrib/amcheck/t/006_gin_concurrency.pl b/contrib/amcheck/t/006_gin_concurrency.pl
new file mode 100644
index 00000000000..afc67940d4d
--- /dev/null
+++ b/contrib/amcheck/t/006_gin_concurrency.pl
@@ -0,0 +1,196 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i integer[], j jsonb, k jsonb)));
+$node->safe_psql('postgres', q(CREATE INDEX ginidx ON tbl USING gin(i, j, k)));
+$node->safe_psql('postgres', q(CREATE TABLE jsondata (i serial, j jsonb)));
+$node->safe_psql('postgres', q(INSERT INTO jsondata (j) VALUES
+	('1'),
+	('91'),
+	('[5]'),
+	('true'),
+	('"zxI"'),
+	('[1, 7]'),
+	('["", 4]'),
+	('"utDFBz"'),
+	('[[9], ""]'),
+	('"eCvxKPML"'),
+	('["1VMQNQM"]'),
+	('{"": "562c"}'),
+	('[58, 8, null]'),
+	('{"": {"": 62}}'),
+	('["", 6, 19, ""]'),
+	('{"ddfWTQ": true}'),
+	('["", 734.2, 9, 5]'),
+	('"GMV27mjtuuqmlltw"'),
+	('{"dabe": -5, "": 6}'),
+	('"hgihykirQGIYTcCA30"'),
+	('[9, {"Utrn": -6}, ""]'),
+	('"BJTZUMST1_WWEgyqgka_"'),
+	('["", -4, "", [-2], -47]'),
+	('{"": [3], "": {"": "y"}}'),
+	('{"myuijj": "YUWIUZXXLGS"}'),
+	('{"3": false, "C": "1sHTX"}'),
+	('"ZGUORVDE_ACF1QXJ_hipgwrks"'),
+	('{"072": [3, -4], "oh": "eL"}'),
+	('[{"de": 9, "JWHPMRZJW": [0]}]'),
+	('"EACJUZEBAFFBEE6706SZLWVGO635"'),
+	('["P", {"TZW": [""]}, {"": [0]}]'),
+	('{"": -6, "YMb": -22, "__": [""]}'),
+	('{"659": [8], "bfc": [0], "V": ""}'),
+	('{"8776": "1tryl", "Q": 2, "": 4.6}'),
+	('[[1], "", 9, 0, [1, 0], -1, 0, "C"]'),
+	('"635321pnpjlfFzhGTIYP9265iA_19D8260"'),
+	('"klmxsoCFDtzxrhotsqlnmvmzlcbdde34twj"'),
+	('"GZSXSZVS19ecbe_ZJJED0379c1j9_GSU9167"'),
+	('{"F18s": {"": -84194}, "ececab2": [""]}'),
+	('["", {"SVAvgg": "Q"}, 1, 9, "gypy", [1]]'),
+	('[[""], {"": 5}, "GVZGGVGSWM", 2, ["", 8]]'),
+	('{"V": 8, "TPNL": [826, null], "4": -9.729}'),
+	('{"HTJP_DAptxn6": 9, "": "r", "hji4124": ""}'),
+	('[1, ["9", 5, 6, ""], {"": "", "": "efb"}, 7]'),
+	('{"": 6, "1251e_cajrgkyzuxBEDM017444EFD": 548}'),
+	('{"853": -60, "TGLUG_jxmrggv": null, "pjx": ""}'),
+	('[0, "wsgnnvCfJVV_KOMLVXOUIS9FIQLPXXBbbaohjrpj"]'),
+	('"nizvkl36908OLW22ecbdeEBMHMiCEEACcikwkjpmu30X_m"'),
+	('{"bD24eeVZWY": 1, "Bt": 9, "": 6052, "FT": ["h"]}'),
+	('"CDBnouyzlAMSHJCtguxxizpzgkNYfaNLURVITNLYVPSNLYNy"'),
+	('{"d": [[4, "N"], null, 6, true], "1PKV": 6, "9": 6}'),
+	('[-7326, [83, 55], -63, [0, {"": 1}], {"ri0": false}]'),
+	('{"": 117.38, "FCkx3608szztpvjolomzvlyrshyvrgz": -4.2}'),
+	('["", 8, {"WXHNG": {"6": 4}}, [null], 7, 2, "", 299, 6]'),
+	('[[-992.2, "TPm", "", "cedeff79BD8", "t", [1]], 0, [-7]]'),
+	('[9, 34, ["LONuyiYGQZ"], [7, 88], ["c"], 1, 6, "", [[2]]]'),
+	('[20, 5, null, "eLHTXRWNV", 8, ["pnpvrum", -3], "FINY", 3]'),
+	('[{"": "", "b": 2, "d": "egu"}, "aPNK", 2, 9, {"": -79946}]'),
+	('[1, {"769": 9}, 5, 9821, 22, 0, 2.7, 5, 4, 191, 54.599, 24]'),
+	('["c", 77, "b_0lplvHJNLMxw", "VN76dhFadaafadfe5dfbco", false]'),
+	('"TYIHXebbPK_86QMP_199bEEIS__8205986vdC_CFAEFBFCEFCJQRHYoqztv"'),
+	('"cdmxxxzrhtxpwuyrxinmhb5577NSPHIHMTPQYTXSUVVGJPUUMCBEDb_1569e"'),
+	('[[5, null, "C"], "ORNR", "mnCb", 1, -800, "6953", ["K", 0], ""]'),
+	('"SSKLTHJxjxywwquhiwsde353eCIJJjkyvn9946c2cdVadcboiyZFAYMHJWGMMT"'),
+	('"5185__D5AtvhizvmEVceF3jxtghlCF0789_owmsztJHRMOJ7rlowxqq51XLXJbF"'),
+	('{"D": 565206, "xupqtmfedff": "ZGJN9", "9": 1, "glzv": -47, "": -8}'),
+	('{"": 9, "": {"": [null], "ROP": 842}, "": ["5FFD", 7, 5, 1, 94, 1]}'),
+	('{"JLn": ["8s"], "": "_ahxizrzhivyzvhr", "XSAt": 5, "P": 2838, "": 5}'),
+	('[51, 3, {"": 9, "": -9, "": [[6]]}, 7, 7, {"": 0}, "TXLQL", 7.6, [7]]'),
+	('[-38.7, "kre40", 5, {"": null}, "tvuv", 8, "", "", "uizygprwwvh", "1"]'),
+	('"z934377_nxmzjnuqglgyukjteefeihjyot1irkvwnnrqinptlpzwjgmkjbQMUVxxwvbdz"'),
+	('[165.9, "dAFD_60JQPYbafh", false, {"": 6, "": "fcfd"}, [[2], "c"], 4, 2]'),
+	('"ffHOOPVSSACDqiyeecTNWJMWPNRXU283aHRXNUNZZZQPUGYSQTTQXQVJM5eeafcIPGIHcac"'),
+	('[2, 8, -53, {"": 5}, "F9", 8, "SGUJPNVI", "7OLOZH", 9.84, {"": 6}, 207, 6]'),
+	('"xqmqmyljhq__ZGWJVNefagsxrsktruhmlinhxloupuVQW0804901NKGGMNNSYYXWQOosz8938"'),
+	('{"FEoLfaab1160167": {"L": [42, 0]}, "938": "FCCUPGYYYMQSQVZJKM", "knqmk": 2}'),
+	('"0igyurmOMSXIYHSZQEAcxlvgqdxkhwtrbaabfaaMC138Z_BDRLrythpi30_MPRXMTOILRLswmoy"'),
+	('"1129BBCABFFAACA9VGVKipnwohaccc9TSIMTOQKHmcGYVeFE_PWKLHmpyj60137672qugtsstugg"'),
+	('"D3BDA069074174vx48A37IVHWVXLUP9382542ypsl1465pixtryzCBgrkkhrvCC_BDDFatkyXHLIe"'),
+	('[{"esx7": -53, "ec60834YGVMYoXAAvgxmmqnojyzmiklhdovFipl": 2, "os": 66433}, 9.13]'),
+	('{"": ["", 4, null, 5, null], "": "3", "5_GMMHTIhPB_F_vsebc1": "Er", "GY": 121.32}'),
+	('["krTVPYDEd", 5, 8, [6, -6], [[-9], 3340, [[""]]], "", 5, [6, true], 3, "", 1, ""]'),
+	('{"rBNPKN8446080wruOLeceaCBDCKWNUYYMONSJUlCDFExr": {"": "EE0", "6826": 5, "": 7496}}'),
+	('[3, {"": -8}, "101dboMVSNKZLVPITLHLPorwwuxxjmjsh", "", "LSQPRVYKWVYK945imrh", 4, 51]'),
+	('[["HY6"], "", "bcdB", [2, [85, 1], 3, 3, 3, [8]], "", ["_m"], "2", -33, 8, 3, "_xwj"]'),
+	('["", 0, -3.7, 8, false, null, {"": 5}, 9, "06FccxFcdb283bbZGGVRSMWLJH2_PBAFpwtkbceto"]'),
+	('[52, "", -39, -7, [1], "c", {"": 9, "": 45528, "G": {"": 7}}, 3, false, 0, "EB", 8, -6]'),
+	('"qzrkvrlG78CCCEBCptzwwok808805243QXVSYed3efZSKLSNXPxhrS357KJMWSKgrfcFFDFDWKSXJJSIJ_yqJu"'),
+	('[43, 8, {"": ""}, "uwtv__HURKGJLGGPPW", 9, 66, "yqrvghxuw", {"J": false}, false, 2, 0, 4]'),
+	('[{"UVL": 7, "": 1}, false, [6, "H"], "boxlgqgm", 3, "znhm", [true], 0, ["e", 3.7], 9, 9.4]'),
+	('{"825634870117somzqw": 1, "": [5], "gYH": "_XT", "b22412631709RZP": 3, "": "", "FDB": [""]}'),
+	('[8, ["_bae"], "", "WN", 80, {"o": 2, "aff": 16}, false, true, 4, 6, {"nutzkzikolsxZRQ": 30}]'),
+	('["588BD9c_xzsn", {"k": 0, "_Ecezlkslrwvjpwrukiqzl": 3, "Ej": "4"}, "TUXwghn1dTNRXJZpswmD", 5]'),
+	('[{"dC": 7}, {"": 1, "4": 41, "": "", "": "adKS"}, {"": "ypv"}, 6, 9, 2, [-61.46], [1, 3.9], 2]'),
+	('{"8": 8, "": -364, "855": -238.1, "zj": 9, "SNHJG413": 3, "UMNVI73": [60, 0], "iwvqse": -1.833}'),
+	('"VTUKMLZKQPHIEniCFZ_cjrhvspxzulvxhqykjzmrw89OGOGISWdcrvpOPLOFALGK809896999xzqnkm63254_xrmcfcedb"'),
+	('["", "USNQbcexyFDCdBAFWJIphloxwytplyZZR008400FmoiYXVYOHVGV79795644463Aug_aeoDDEjzoziisxoykuijhz"]'),
+	('{"": 1, "5abB58gXVQVTTMWU3jSHXMMNV": "", "nv": 934, "kjsnhtj": 8, "": [{"xm": [71, 425]}], "": -9}'),
+	('"__oliqCcbwwyqmtECsqivplcb1NTMOQRZTYRJONOIPWNHKWLJRIHKROMJNZLNGTTKRcedebccdbMTQXSzhynxmllqxuhnxBA_"'),
+	('["thgACBWGNGMkFFEA", [0, -1349, {"18": "RM", "F3": 6, "dP": "_AF"}, 64, 0, {"f": [8]}], 5, [[0]], 2]')
+));
+
+#
+# Stress gin with pgbench.
+#
+# Modify the table data, and hence the index data, from multiple process
+# while from other processes run the index checking code.  This should,
+# if the index is large enough, result in the checks performing across
+# concurrent page splits.
+#
+$node->pgbench(
+	'--no-vacuum --client=20 --transactions=5000',
+	0,
+	[qr{actually processed}],
+	[qr{^$}],
+	'concurrent DML and index checking',
+	{
+		'006_gin_concurrency_insert_1' => q(
+			INSERT INTO tbl (i, j, k)
+				(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+					FROM jsondata x, jsondata y
+					WHERE x.i = random(1,100)
+					  AND y.i = random(1,100)
+				)
+		  ),
+		'006_gin_concurrency_insert_2' => q(
+			INSERT INTO tbl (i, j, k)
+				(SELECT gs.i, j.j, j.j || j.j
+					FROM jsondata j,
+						 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+					WHERE j.i = random(1,100)
+				)
+		  ),
+		'006_gin_concurrency_insert_nulls' => q(
+			INSERT INTO tbl (i, j, k) VALUES
+				(null,               null, null),
+				(null,               null, '[]'),
+				(null,               '[]', null),
+				(ARRAY[]::INTEGER[], null, null),
+				(null,               '[]', '[]'),
+				(ARRAY[]::INTEGER[], '[]', null),
+				(ARRAY[]::INTEGER[], '[]', '[]')
+		  ),
+		'006_gin_concurrency_update_i' => q(
+			UPDATE tbl
+				SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+				WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_update_j' => q(
+			UPDATE tbl
+				SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+				WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_update_k' => q(
+			UPDATE tbl
+				SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+				WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_delete' => q(
+			DELETE FROM tbl
+				WHERE random(1,5) = 3;
+		),
+		'006_gin_concurrency_gin_index_check' => q(
+				SELECT gin_index_check('ginidx');
+		)
+	});
+
+$node->stop;
+done_testing();
+
-- 
2.39.3 (Apple Git-145)

From d2ec9b8f77bf40ed258f5d12bc58877b6f1109ef Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 14:45:12 -0800
Subject: [PATCH v0] Add a reproducible test case for verify_gin errors

The test t/006_gin_concurrency.pl works fairly well at triggering
the bug, at least for me, but it is hard to step through a TAP test.
Convert the statements in the log output of a failed TAP run into a
regression test, and find a setseed() value that makes it
deterministically fail, and add that test.

If you use this test and it does not fail, perhaps that is due to
architectural differences between your system and my laptop.  I
found that I could find a seed by guess-and-check within no more
than 10 attempts, so the reader can probably do likewise.
---
 contrib/amcheck/Makefile                |     2 +-
 contrib/amcheck/expected/stress_gin.out | 12925 ++++++++++++++++++++++
 contrib/amcheck/sql/stress_gin.sql      | 11432 +++++++++++++++++++
 3 files changed, 24358 insertions(+), 1 deletion(-)
 create mode 100644 contrib/amcheck/expected/stress_gin.out
 create mode 100644 contrib/amcheck/sql/stress_gin.sql

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 1b7a63cbaa4..66686f522ff 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -13,7 +13,7 @@ DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck
 		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_gin check_heap
+REGRESS = check check_btree check_gin check_heap stress_gin
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/expected/stress_gin.out b/contrib/amcheck/expected/stress_gin.out
new file mode 100644
index 00000000000..e2ace3cbf13
--- /dev/null
+++ b/contrib/amcheck/expected/stress_gin.out
@@ -0,0 +1,12925 @@
+SELECT setseed(0.2);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE tbl(i integer[], j jsonb, k jsonb);
+CREATE INDEX ginidx ON tbl USING gin(i, j, k);
+CREATE TABLE jsondata (i serial, j jsonb);
+INSERT INTO jsondata (j) VALUES
+	('1'),
+	('91'),
+	('[5]'),
+	('true'),
+	('"zxI"'),
+	('[1, 7]'),
+	('["", 4]'),
+	('"utDFBz"'),
+	('[[9], ""]'),
+	('"eCvxKPML"'),
+	('["1VMQNQM"]'),
+	('{"": "562c"}'),
+	('[58, 8, null]'),
+	('{"": {"": 62}}'),
+	('["", 6, 19, ""]'),
+	('{"ddfWTQ": true}'),
+	('["", 734.2, 9, 5]'),
+	('"GMV27mjtuuqmlltw"'),
+	('{"dabe": -5, "": 6}'),
+	('"hgihykirQGIYTcCA30"'),
+	('[9, {"Utrn": -6}, ""]'),
+	('"BJTZUMST1_WWEgyqgka_"'),
+	('["", -4, "", [-2], -47]'),
+	('{"": [3], "": {"": "y"}}'),
+	('{"myuijj": "YUWIUZXXLGS"}'),
+	('{"3": false, "C": "1sHTX"}'),
+	('"ZGUORVDE_ACF1QXJ_hipgwrks"'),
+	('{"072": [3, -4], "oh": "eL"}'),
+	('[{"de": 9, "JWHPMRZJW": [0]}]'),
+	('"EACJUZEBAFFBEE6706SZLWVGO635"'),
+	('["P", {"TZW": [""]}, {"": [0]}]'),
+	('{"": -6, "YMb": -22, "__": [""]}'),
+	('{"659": [8], "bfc": [0], "V": ""}'),
+	('{"8776": "1tryl", "Q": 2, "": 4.6}'),
+	('[[1], "", 9, 0, [1, 0], -1, 0, "C"]'),
+	('"635321pnpjlfFzhGTIYP9265iA_19D8260"'),
+	('"klmxsoCFDtzxrhotsqlnmvmzlcbdde34twj"'),
+	('"GZSXSZVS19ecbe_ZJJED0379c1j9_GSU9167"'),
+	('{"F18s": {"": -84194}, "ececab2": [""]}'),
+	('["", {"SVAvgg": "Q"}, 1, 9, "gypy", [1]]'),
+	('[[""], {"": 5}, "GVZGGVGSWM", 2, ["", 8]]'),
+	('{"V": 8, "TPNL": [826, null], "4": -9.729}'),
+	('{"HTJP_DAptxn6": 9, "": "r", "hji4124": ""}'),
+	('[1, ["9", 5, 6, ""], {"": "", "": "efb"}, 7]'),
+	('{"": 6, "1251e_cajrgkyzuxBEDM017444EFD": 548}'),
+	('{"853": -60, "TGLUG_jxmrggv": null, "pjx": ""}'),
+	('[0, "wsgnnvCfJVV_KOMLVXOUIS9FIQLPXXBbbaohjrpj"]'),
+	('"nizvkl36908OLW22ecbdeEBMHMiCEEACcikwkjpmu30X_m"'),
+	('{"bD24eeVZWY": 1, "Bt": 9, "": 6052, "FT": ["h"]}'),
+	('"CDBnouyzlAMSHJCtguxxizpzgkNYfaNLURVITNLYVPSNLYNy"'),
+	('{"d": [[4, "N"], null, 6, true], "1PKV": 6, "9": 6}'),
+	('[-7326, [83, 55], -63, [0, {"": 1}], {"ri0": false}]'),
+	('{"": 117.38, "FCkx3608szztpvjolomzvlyrshyvrgz": -4.2}'),
+	('["", 8, {"WXHNG": {"6": 4}}, [null], 7, 2, "", 299, 6]'),
+	('[[-992.2, "TPm", "", "cedeff79BD8", "t", [1]], 0, [-7]]'),
+	('[9, 34, ["LONuyiYGQZ"], [7, 88], ["c"], 1, 6, "", [[2]]]'),
+	('[20, 5, null, "eLHTXRWNV", 8, ["pnpvrum", -3], "FINY", 3]'),
+	('[{"": "", "b": 2, "d": "egu"}, "aPNK", 2, 9, {"": -79946}]'),
+	('[1, {"769": 9}, 5, 9821, 22, 0, 2.7, 5, 4, 191, 54.599, 24]'),
+	('["c", 77, "b_0lplvHJNLMxw", "VN76dhFadaafadfe5dfbco", false]'),
+	('"TYIHXebbPK_86QMP_199bEEIS__8205986vdC_CFAEFBFCEFCJQRHYoqztv"'),
+	('"cdmxxxzrhtxpwuyrxinmhb5577NSPHIHMTPQYTXSUVVGJPUUMCBEDb_1569e"'),
+	('[[5, null, "C"], "ORNR", "mnCb", 1, -800, "6953", ["K", 0], ""]'),
+	('"SSKLTHJxjxywwquhiwsde353eCIJJjkyvn9946c2cdVadcboiyZFAYMHJWGMMT"'),
+	('"5185__D5AtvhizvmEVceF3jxtghlCF0789_owmsztJHRMOJ7rlowxqq51XLXJbF"'),
+	('{"D": 565206, "xupqtmfedff": "ZGJN9", "9": 1, "glzv": -47, "": -8}'),
+	('{"": 9, "": {"": [null], "ROP": 842}, "": ["5FFD", 7, 5, 1, 94, 1]}'),
+	('{"JLn": ["8s"], "": "_ahxizrzhivyzvhr", "XSAt": 5, "P": 2838, "": 5}'),
+	('[51, 3, {"": 9, "": -9, "": [[6]]}, 7, 7, {"": 0}, "TXLQL", 7.6, [7]]'),
+	('[-38.7, "kre40", 5, {"": null}, "tvuv", 8, "", "", "uizygprwwvh", "1"]'),
+	('"z934377_nxmzjnuqglgyukjteefeihjyot1irkvwnnrqinptlpzwjgmkjbQMUVxxwvbdz"'),
+	('[165.9, "dAFD_60JQPYbafh", false, {"": 6, "": "fcfd"}, [[2], "c"], 4, 2]'),
+	('"ffHOOPVSSACDqiyeecTNWJMWPNRXU283aHRXNUNZZZQPUGYSQTTQXQVJM5eeafcIPGIHcac"'),
+	('[2, 8, -53, {"": 5}, "F9", 8, "SGUJPNVI", "7OLOZH", 9.84, {"": 6}, 207, 6]'),
+	('"xqmqmyljhq__ZGWJVNefagsxrsktruhmlinhxloupuVQW0804901NKGGMNNSYYXWQOosz8938"'),
+	('{"FEoLfaab1160167": {"L": [42, 0]}, "938": "FCCUPGYYYMQSQVZJKM", "knqmk": 2}'),
+	('"0igyurmOMSXIYHSZQEAcxlvgqdxkhwtrbaabfaaMC138Z_BDRLrythpi30_MPRXMTOILRLswmoy"'),
+	('"1129BBCABFFAACA9VGVKipnwohaccc9TSIMTOQKHmcGYVeFE_PWKLHmpyj60137672qugtsstugg"'),
+	('"D3BDA069074174vx48A37IVHWVXLUP9382542ypsl1465pixtryzCBgrkkhrvCC_BDDFatkyXHLIe"'),
+	('[{"esx7": -53, "ec60834YGVMYoXAAvgxmmqnojyzmiklhdovFipl": 2, "os": 66433}, 9.13]'),
+	('{"": ["", 4, null, 5, null], "": "3", "5_GMMHTIhPB_F_vsebc1": "Er", "GY": 121.32}'),
+	('["krTVPYDEd", 5, 8, [6, -6], [[-9], 3340, [[""]]], "", 5, [6, true], 3, "", 1, ""]'),
+	('{"rBNPKN8446080wruOLeceaCBDCKWNUYYMONSJUlCDFExr": {"": "EE0", "6826": 5, "": 7496}}'),
+	('[3, {"": -8}, "101dboMVSNKZLVPITLHLPorwwuxxjmjsh", "", "LSQPRVYKWVYK945imrh", 4, 51]'),
+	('[["HY6"], "", "bcdB", [2, [85, 1], 3, 3, 3, [8]], "", ["_m"], "2", -33, 8, 3, "_xwj"]'),
+	('["", 0, -3.7, 8, false, null, {"": 5}, 9, "06FccxFcdb283bbZGGVRSMWLJH2_PBAFpwtkbceto"]'),
+	('[52, "", -39, -7, [1], "c", {"": 9, "": 45528, "G": {"": 7}}, 3, false, 0, "EB", 8, -6]'),
+	('"qzrkvrlG78CCCEBCptzwwok808805243QXVSYed3efZSKLSNXPxhrS357KJMWSKgrfcFFDFDWKSXJJSIJ_yqJu"'),
+	('[43, 8, {"": ""}, "uwtv__HURKGJLGGPPW", 9, 66, "yqrvghxuw", {"J": false}, false, 2, 0, 4]'),
+	('[{"UVL": 7, "": 1}, false, [6, "H"], "boxlgqgm", 3, "znhm", [true], 0, ["e", 3.7], 9, 9.4]'),
+	('{"825634870117somzqw": 1, "": [5], "gYH": "_XT", "b22412631709RZP": 3, "": "", "FDB": [""]}'),
+	('[8, ["_bae"], "", "WN", 80, {"o": 2, "aff": 16}, false, true, 4, 6, {"nutzkzikolsxZRQ": 30}]'),
+	('["588BD9c_xzsn", {"k": 0, "_Ecezlkslrwvjpwrukiqzl": 3, "Ej": "4"}, "TUXwghn1dTNRXJZpswmD", 5]'),
+	('[{"dC": 7}, {"": 1, "4": 41, "": "", "": "adKS"}, {"": "ypv"}, 6, 9, 2, [-61.46], [1, 3.9], 2]'),
+	('{"8": 8, "": -364, "855": -238.1, "zj": 9, "SNHJG413": 3, "UMNVI73": [60, 0], "iwvqse": -1.833}'),
+	('"VTUKMLZKQPHIEniCFZ_cjrhvspxzulvxhqykjzmrw89OGOGISWdcrvpOPLOFALGK809896999xzqnkm63254_xrmcfcedb"'),
+	('["", "USNQbcexyFDCdBAFWJIphloxwytplyZZR008400FmoiYXVYOHVGV79795644463Aug_aeoDDEjzoziisxoykuijhz"]'),
+	('{"": 1, "5abB58gXVQVTTMWU3jSHXMMNV": "", "nv": 934, "kjsnhtj": 8, "": [{"xm": [71, 425]}], "": -9}'),
+	('"__oliqCcbwwyqmtECsqivplcb1NTMOQRZTYRJONOIPWNHKWLJRIHKROMJNZLNGTTKRcedebccdbMTQXSzhynxmllqxuhnxBA_"'),
+	('["thgACBWGNGMkFFEA", [0, -1349, {"18": "RM", "F3": 6, "dP": "_AF"}, 64, 0, {"f": [8]}], 5, [[0]], 2]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
diff --git a/contrib/amcheck/sql/stress_gin.sql b/contrib/amcheck/sql/stress_gin.sql
new file mode 100644
index 00000000000..881a7d442a5
--- /dev/null
+++ b/contrib/amcheck/sql/stress_gin.sql
@@ -0,0 +1,11432 @@
+SELECT setseed(0.2);
+CREATE TABLE tbl(i integer[], j jsonb, k jsonb);
+CREATE INDEX ginidx ON tbl USING gin(i, j, k);
+CREATE TABLE jsondata (i serial, j jsonb);
+INSERT INTO jsondata (j) VALUES
+	('1'),
+	('91'),
+	('[5]'),
+	('true'),
+	('"zxI"'),
+	('[1, 7]'),
+	('["", 4]'),
+	('"utDFBz"'),
+	('[[9], ""]'),
+	('"eCvxKPML"'),
+	('["1VMQNQM"]'),
+	('{"": "562c"}'),
+	('[58, 8, null]'),
+	('{"": {"": 62}}'),
+	('["", 6, 19, ""]'),
+	('{"ddfWTQ": true}'),
+	('["", 734.2, 9, 5]'),
+	('"GMV27mjtuuqmlltw"'),
+	('{"dabe": -5, "": 6}'),
+	('"hgihykirQGIYTcCA30"'),
+	('[9, {"Utrn": -6}, ""]'),
+	('"BJTZUMST1_WWEgyqgka_"'),
+	('["", -4, "", [-2], -47]'),
+	('{"": [3], "": {"": "y"}}'),
+	('{"myuijj": "YUWIUZXXLGS"}'),
+	('{"3": false, "C": "1sHTX"}'),
+	('"ZGUORVDE_ACF1QXJ_hipgwrks"'),
+	('{"072": [3, -4], "oh": "eL"}'),
+	('[{"de": 9, "JWHPMRZJW": [0]}]'),
+	('"EACJUZEBAFFBEE6706SZLWVGO635"'),
+	('["P", {"TZW": [""]}, {"": [0]}]'),
+	('{"": -6, "YMb": -22, "__": [""]}'),
+	('{"659": [8], "bfc": [0], "V": ""}'),
+	('{"8776": "1tryl", "Q": 2, "": 4.6}'),
+	('[[1], "", 9, 0, [1, 0], -1, 0, "C"]'),
+	('"635321pnpjlfFzhGTIYP9265iA_19D8260"'),
+	('"klmxsoCFDtzxrhotsqlnmvmzlcbdde34twj"'),
+	('"GZSXSZVS19ecbe_ZJJED0379c1j9_GSU9167"'),
+	('{"F18s": {"": -84194}, "ececab2": [""]}'),
+	('["", {"SVAvgg": "Q"}, 1, 9, "gypy", [1]]'),
+	('[[""], {"": 5}, "GVZGGVGSWM", 2, ["", 8]]'),
+	('{"V": 8, "TPNL": [826, null], "4": -9.729}'),
+	('{"HTJP_DAptxn6": 9, "": "r", "hji4124": ""}'),
+	('[1, ["9", 5, 6, ""], {"": "", "": "efb"}, 7]'),
+	('{"": 6, "1251e_cajrgkyzuxBEDM017444EFD": 548}'),
+	('{"853": -60, "TGLUG_jxmrggv": null, "pjx": ""}'),
+	('[0, "wsgnnvCfJVV_KOMLVXOUIS9FIQLPXXBbbaohjrpj"]'),
+	('"nizvkl36908OLW22ecbdeEBMHMiCEEACcikwkjpmu30X_m"'),
+	('{"bD24eeVZWY": 1, "Bt": 9, "": 6052, "FT": ["h"]}'),
+	('"CDBnouyzlAMSHJCtguxxizpzgkNYfaNLURVITNLYVPSNLYNy"'),
+	('{"d": [[4, "N"], null, 6, true], "1PKV": 6, "9": 6}'),
+	('[-7326, [83, 55], -63, [0, {"": 1}], {"ri0": false}]'),
+	('{"": 117.38, "FCkx3608szztpvjolomzvlyrshyvrgz": -4.2}'),
+	('["", 8, {"WXHNG": {"6": 4}}, [null], 7, 2, "", 299, 6]'),
+	('[[-992.2, "TPm", "", "cedeff79BD8", "t", [1]], 0, [-7]]'),
+	('[9, 34, ["LONuyiYGQZ"], [7, 88], ["c"], 1, 6, "", [[2]]]'),
+	('[20, 5, null, "eLHTXRWNV", 8, ["pnpvrum", -3], "FINY", 3]'),
+	('[{"": "", "b": 2, "d": "egu"}, "aPNK", 2, 9, {"": -79946}]'),
+	('[1, {"769": 9}, 5, 9821, 22, 0, 2.7, 5, 4, 191, 54.599, 24]'),
+	('["c", 77, "b_0lplvHJNLMxw", "VN76dhFadaafadfe5dfbco", false]'),
+	('"TYIHXebbPK_86QMP_199bEEIS__8205986vdC_CFAEFBFCEFCJQRHYoqztv"'),
+	('"cdmxxxzrhtxpwuyrxinmhb5577NSPHIHMTPQYTXSUVVGJPUUMCBEDb_1569e"'),
+	('[[5, null, "C"], "ORNR", "mnCb", 1, -800, "6953", ["K", 0], ""]'),
+	('"SSKLTHJxjxywwquhiwsde353eCIJJjkyvn9946c2cdVadcboiyZFAYMHJWGMMT"'),
+	('"5185__D5AtvhizvmEVceF3jxtghlCF0789_owmsztJHRMOJ7rlowxqq51XLXJbF"'),
+	('{"D": 565206, "xupqtmfedff": "ZGJN9", "9": 1, "glzv": -47, "": -8}'),
+	('{"": 9, "": {"": [null], "ROP": 842}, "": ["5FFD", 7, 5, 1, 94, 1]}'),
+	('{"JLn": ["8s"], "": "_ahxizrzhivyzvhr", "XSAt": 5, "P": 2838, "": 5}'),
+	('[51, 3, {"": 9, "": -9, "": [[6]]}, 7, 7, {"": 0}, "TXLQL", 7.6, [7]]'),
+	('[-38.7, "kre40", 5, {"": null}, "tvuv", 8, "", "", "uizygprwwvh", "1"]'),
+	('"z934377_nxmzjnuqglgyukjteefeihjyot1irkvwnnrqinptlpzwjgmkjbQMUVxxwvbdz"'),
+	('[165.9, "dAFD_60JQPYbafh", false, {"": 6, "": "fcfd"}, [[2], "c"], 4, 2]'),
+	('"ffHOOPVSSACDqiyeecTNWJMWPNRXU283aHRXNUNZZZQPUGYSQTTQXQVJM5eeafcIPGIHcac"'),
+	('[2, 8, -53, {"": 5}, "F9", 8, "SGUJPNVI", "7OLOZH", 9.84, {"": 6}, 207, 6]'),
+	('"xqmqmyljhq__ZGWJVNefagsxrsktruhmlinhxloupuVQW0804901NKGGMNNSYYXWQOosz8938"'),
+	('{"FEoLfaab1160167": {"L": [42, 0]}, "938": "FCCUPGYYYMQSQVZJKM", "knqmk": 2}'),
+	('"0igyurmOMSXIYHSZQEAcxlvgqdxkhwtrbaabfaaMC138Z_BDRLrythpi30_MPRXMTOILRLswmoy"'),
+	('"1129BBCABFFAACA9VGVKipnwohaccc9TSIMTOQKHmcGYVeFE_PWKLHmpyj60137672qugtsstugg"'),
+	('"D3BDA069074174vx48A37IVHWVXLUP9382542ypsl1465pixtryzCBgrkkhrvCC_BDDFatkyXHLIe"'),
+	('[{"esx7": -53, "ec60834YGVMYoXAAvgxmmqnojyzmiklhdovFipl": 2, "os": 66433}, 9.13]'),
+	('{"": ["", 4, null, 5, null], "": "3", "5_GMMHTIhPB_F_vsebc1": "Er", "GY": 121.32}'),
+	('["krTVPYDEd", 5, 8, [6, -6], [[-9], 3340, [[""]]], "", 5, [6, true], 3, "", 1, ""]'),
+	('{"rBNPKN8446080wruOLeceaCBDCKWNUYYMONSJUlCDFExr": {"": "EE0", "6826": 5, "": 7496}}'),
+	('[3, {"": -8}, "101dboMVSNKZLVPITLHLPorwwuxxjmjsh", "", "LSQPRVYKWVYK945imrh", 4, 51]'),
+	('[["HY6"], "", "bcdB", [2, [85, 1], 3, 3, 3, [8]], "", ["_m"], "2", -33, 8, 3, "_xwj"]'),
+	('["", 0, -3.7, 8, false, null, {"": 5}, 9, "06FccxFcdb283bbZGGVRSMWLJH2_PBAFpwtkbceto"]'),
+	('[52, "", -39, -7, [1], "c", {"": 9, "": 45528, "G": {"": 7}}, 3, false, 0, "EB", 8, -6]'),
+	('"qzrkvrlG78CCCEBCptzwwok808805243QXVSYed3efZSKLSNXPxhrS357KJMWSKgrfcFFDFDWKSXJJSIJ_yqJu"'),
+	('[43, 8, {"": ""}, "uwtv__HURKGJLGGPPW", 9, 66, "yqrvghxuw", {"J": false}, false, 2, 0, 4]'),
+	('[{"UVL": 7, "": 1}, false, [6, "H"], "boxlgqgm", 3, "znhm", [true], 0, ["e", 3.7], 9, 9.4]'),
+	('{"825634870117somzqw": 1, "": [5], "gYH": "_XT", "b22412631709RZP": 3, "": "", "FDB": [""]}'),
+	('[8, ["_bae"], "", "WN", 80, {"o": 2, "aff": 16}, false, true, 4, 6, {"nutzkzikolsxZRQ": 30}]'),
+	('["588BD9c_xzsn", {"k": 0, "_Ecezlkslrwvjpwrukiqzl": 3, "Ej": "4"}, "TUXwghn1dTNRXJZpswmD", 5]'),
+	('[{"dC": 7}, {"": 1, "4": 41, "": "", "": "adKS"}, {"": "ypv"}, 6, 9, 2, [-61.46], [1, 3.9], 2]'),
+	('{"8": 8, "": -364, "855": -238.1, "zj": 9, "SNHJG413": 3, "UMNVI73": [60, 0], "iwvqse": -1.833}'),
+	('"VTUKMLZKQPHIEniCFZ_cjrhvspxzulvxhqykjzmrw89OGOGISWdcrvpOPLOFALGK809896999xzqnkm63254_xrmcfcedb"'),
+	('["", "USNQbcexyFDCdBAFWJIphloxwytplyZZR008400FmoiYXVYOHVGV79795644463Aug_aeoDDEjzoziisxoykuijhz"]'),
+	('{"": 1, "5abB58gXVQVTTMWU3jSHXMMNV": "", "nv": 934, "kjsnhtj": 8, "": [{"xm": [71, 425]}], "": -9}'),
+	('"__oliqCcbwwyqmtECsqivplcb1NTMOQRZTYRJONOIPWNHKWLJRIHKROMJNZLNGTTKRcedebccdbMTQXSzhynxmllqxuhnxBA_"'),
+	('["thgACBWGNGMkFFEA", [0, -1349, {"18": "RM", "F3": 6, "dP": "_AF"}, 64, 0, {"f": [8]}], 5, [[0]], 2]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+UPDATE tbl
+	SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+	WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+DELETE FROM tbl
+	WHERE random(1,5) = 3;
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
+UPDATE tbl
+	SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+	WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
+SELECT gin_index_check('ginidx');
-- 
2.39.3 (Apple Git-145)

From 657a26e191b97ce3d4868a97178a61969dfe2dff Mon Sep 17 00:00:00 2001
From: reshke <reshkekirill@gmail.com>
Date: Fri, 28 Feb 2025 06:11:58 +0000
Subject: [PATCH] Much smaller repro

---
 contrib/amcheck/stress_gin_3.sql | 145 +++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 contrib/amcheck/stress_gin_3.sql

diff --git a/contrib/amcheck/stress_gin_3.sql b/contrib/amcheck/stress_gin_3.sql
new file mode 100644
index 00000000000..0d73947c87b
--- /dev/null
+++ b/contrib/amcheck/stress_gin_3.sql
@@ -0,0 +1,145 @@
+CREATE EXTENSION amcheck;
+SELECT setseed(0.2);
+CREATE TABLE tbl(i integer[], j jsonb, k jsonb);
+CREATE INDEX ginidx ON tbl USING gin(i, j, k) WITH (fastupdate=false, gin_pending_list_limit=64);
+CREATE TABLE jsondata (i serial, j jsonb);
+INSERT INTO jsondata (j) VALUES
+	('1'),
+	('91'),
+	('[5]'),
+	('true'),
+	('"zxI"'),
+	('[1, 7]'),
+	('["", 4]'),
+	('"utDFBz"'),
+	('[[9], ""]'),
+	('"eCvxKPML"'),
+	('["1VMQNQM"]'),
+	('{"": "562c"}'),
+	('[58, 8, null]'),
+	('{"": {"": 62}}'),
+	('["", 6, 19, ""]'),
+	('{"ddfWTQ": true}'),
+	('["", 734.2, 9, 5]'),
+	('"GMV27mjtuuqmlltw"'),
+	('{"dabe": -5, "": 6}'),
+	('"hgihykirQGIYTcCA30"'),
+	('[9, {"Utrn": -6}, ""]'),
+	('"BJTZUMST1_WWEgyqgka_"'),
+	('["", -4, "", [-2], -47]'),
+	('{"": [3], "": {"": "y"}}'),
+	('{"myuijj": "YUWIUZXXLGS"}'),
+	('{"3": false, "C": "1sHTX"}'),
+	('"ZGUORVDE_ACF1QXJ_hipgwrks"'),
+	('{"072": [3, -4], "oh": "eL"}'),
+	('[{"de": 9, "JWHPMRZJW": [0]}]'),
+	('"EACJUZEBAFFBEE6706SZLWVGO635"'),
+	('["P", {"TZW": [""]}, {"": [0]}]'),
+	('{"": -6, "YMb": -22, "__": [""]}'),
+	('{"659": [8], "bfc": [0], "V": ""}'),
+	('{"8776": "1tryl", "Q": 2, "": 4.6}'),
+	('[[1], "", 9, 0, [1, 0], -1, 0, "C"]'),
+	('"635321pnpjlfFzhGTIYP9265iA_19D8260"'),
+	('"klmxsoCFDtzxrhotsqlnmvmzlcbdde34twj"'),
+	('"GZSXSZVS19ecbe_ZJJED0379c1j9_GSU9167"'),
+	('{"F18s": {"": -84194}, "ececab2": [""]}'),
+	('["", {"SVAvgg": "Q"}, 1, 9, "gypy", [1]]'),
+	('[[""], {"": 5}, "GVZGGVGSWM", 2, ["", 8]]'),
+	('{"V": 8, "TPNL": [826, null], "4": -9.729}'),
+	('{"HTJP_DAptxn6": 9, "": "r", "hji4124": ""}'),
+	('[1, ["9", 5, 6, ""], {"": "", "": "efb"}, 7]'),
+	('{"": 6, "1251e_cajrgkyzuxBEDM017444EFD": 548}'),
+	('{"853": -60, "TGLUG_jxmrggv": null, "pjx": ""}'),
+	('[0, "wsgnnvCfJVV_KOMLVXOUIS9FIQLPXXBbbaohjrpj"]'),
+	('"nizvkl36908OLW22ecbdeEBMHMiCEEACcikwkjpmu30X_m"'),
+	('{"bD24eeVZWY": 1, "Bt": 9, "": 6052, "FT": ["h"]}'),
+	('"CDBnouyzlAMSHJCtguxxizpzgkNYfaNLURVITNLYVPSNLYNy"'),
+	('{"d": [[4, "N"], null, 6, true], "1PKV": 6, "9": 6}'),
+	('[-7326, [83, 55], -63, [0, {"": 1}], {"ri0": false}]'),
+	('{"": 117.38, "FCkx3608szztpvjolomzvlyrshyvrgz": -4.2}'),
+	('["", 8, {"WXHNG": {"6": 4}}, [null], 7, 2, "", 299, 6]'),
+	('[[-992.2, "TPm", "", "cedeff79BD8", "t", [1]], 0, [-7]]'),
+	('[9, 34, ["LONuyiYGQZ"], [7, 88], ["c"], 1, 6, "", [[2]]]'),
+	('[20, 5, null, "eLHTXRWNV", 8, ["pnpvrum", -3], "FINY", 3]'),
+	('[{"": "", "b": 2, "d": "egu"}, "aPNK", 2, 9, {"": -79946}]'),
+	('[1, {"769": 9}, 5, 9821, 22, 0, 2.7, 5, 4, 191, 54.599, 24]'),
+	('["c", 77, "b_0lplvHJNLMxw", "VN76dhFadaafadfe5dfbco", false]'),
+	('"TYIHXebbPK_86QMP_199bEEIS__8205986vdC_CFAEFBFCEFCJQRHYoqztv"'),
+	('"cdmxxxzrhtxpwuyrxinmhb5577NSPHIHMTPQYTXSUVVGJPUUMCBEDb_1569e"'),
+	('[[5, null, "C"], "ORNR", "mnCb", 1, -800, "6953", ["K", 0], ""]'),
+	('"SSKLTHJxjxywwquhiwsde353eCIJJjkyvn9946c2cdVadcboiyZFAYMHJWGMMT"'),
+	('"5185__D5AtvhizvmEVceF3jxtghlCF0789_owmsztJHRMOJ7rlowxqq51XLXJbF"'),
+	('{"D": 565206, "xupqtmfedff": "ZGJN9", "9": 1, "glzv": -47, "": -8}'),
+	('{"": 9, "": {"": [null], "ROP": 842}, "": ["5FFD", 7, 5, 1, 94, 1]}'),
+	('{"JLn": ["8s"], "": "_ahxizrzhivyzvhr", "XSAt": 5, "P": 2838, "": 5}'),
+	('[51, 3, {"": 9, "": -9, "": [[6]]}, 7, 7, {"": 0}, "TXLQL", 7.6, [7]]'),
+	('[-38.7, "kre40", 5, {"": null}, "tvuv", 8, "", "", "uizygprwwvh", "1"]'),
+	('"z934377_nxmzjnuqglgyukjteefeihjyot1irkvwnnrqinptlpzwjgmkjbQMUVxxwvbdz"'),
+	('[165.9, "dAFD_60JQPYbafh", false, {"": 6, "": "fcfd"}, [[2], "c"], 4, 2]'),
+	('"ffHOOPVSSACDqiyeecTNWJMWPNRXU283aHRXNUNZZZQPUGYSQTTQXQVJM5eeafcIPGIHcac"'),
+	('[2, 8, -53, {"": 5}, "F9", 8, "SGUJPNVI", "7OLOZH", 9.84, {"": 6}, 207, 6]'),
+	('"xqmqmyljhq__ZGWJVNefagsxrsktruhmlinhxloupuVQW0804901NKGGMNNSYYXWQOosz8938"'),
+	('{"FEoLfaab1160167": {"L": [42, 0]}, "938": "FCCUPGYYYMQSQVZJKM", "knqmk": 2}'),
+	('"0igyurmOMSXIYHSZQEAcxlvgqdxkhwtrbaabfaaMC138Z_BDRLrythpi30_MPRXMTOILRLswmoy"'),
+	('"1129BBCABFFAACA9VGVKipnwohaccc9TSIMTOQKHmcGYVeFE_PWKLHmpyj60137672qugtsstugg"'),
+	('"D3BDA069074174vx48A37IVHWVXLUP9382542ypsl1465pixtryzCBgrkkhrvCC_BDDFatkyXHLIe"'),
+	('[{"esx7": -53, "ec60834YGVMYoXAAvgxmmqnojyzmiklhdovFipl": 2, "os": 66433}, 9.13]'),
+	('{"": ["", 4, null, 5, null], "": "3", "5_GMMHTIhPB_F_vsebc1": "Er", "GY": 121.32}'),
+	('["krTVPYDEd", 5, 8, [6, -6], [[-9], 3340, [[""]]], "", 5, [6, true], 3, "", 1, ""]'),
+	('{"rBNPKN8446080wruOLeceaCBDCKWNUYYMONSJUlCDFExr": {"": "EE0", "6826": 5, "": 7496}}'),
+	('[3, {"": -8}, "101dboMVSNKZLVPITLHLPorwwuxxjmjsh", "", "LSQPRVYKWVYK945imrh", 4, 51]'),
+	('[["HY6"], "", "bcdB", [2, [85, 1], 3, 3, 3, [8]], "", ["_m"], "2", -33, 8, 3, "_xwj"]'),
+	('["", 0, -3.7, 8, false, null, {"": 5}, 9, "06FccxFcdb283bbZGGVRSMWLJH2_PBAFpwtkbceto"]'),
+	('[52, "", -39, -7, [1], "c", {"": 9, "": 45528, "G": {"": 7}}, 3, false, 0, "EB", 8, -6]'),
+	('"qzrkvrlG78CCCEBCptzwwok808805243QXVSYed3efZSKLSNXPxhrS357KJMWSKgrfcFFDFDWKSXJJSIJ_yqJu"'),
+	('[43, 8, {"": ""}, "uwtv__HURKGJLGGPPW", 9, 66, "yqrvghxuw", {"J": false}, false, 2, 0, 4]'),
+	('[{"UVL": 7, "": 1}, false, [6, "H"], "boxlgqgm", 3, "znhm", [true], 0, ["e", 3.7], 9, 9.4]'),
+	('{"825634870117somzqw": 1, "": [5], "gYH": "_XT", "b22412631709RZP": 3, "": "", "FDB": [""]}'),
+	('[8, ["_bae"], "", "WN", 80, {"o": 2, "aff": 16}, false, true, 4, 6, {"nutzkzikolsxZRQ": 30}]'),
+	('["588BD9c_xzsn", {"k": 0, "_Ecezlkslrwvjpwrukiqzl": 3, "Ej": "4"}, "TUXwghn1dTNRXJZpswmD", 5]'),
+	('[{"dC": 7}, {"": 1, "4": 41, "": "", "": "adKS"}, {"": "ypv"}, 6, 9, 2, [-61.46], [1, 3.9], 2]'),
+	('{"8": 8, "": -364, "855": -238.1, "zj": 9, "SNHJG413": 3, "UMNVI73": [60, 0], "iwvqse": -1.833}'),
+	('"VTUKMLZKQPHIEniCFZ_cjrhvspxzulvxhqykjzmrw89OGOGISWdcrvpOPLOFALGK809896999xzqnkm63254_xrmcfcedb"'),
+	('["", "USNQbcexyFDCdBAFWJIphloxwytplyZZR008400FmoiYXVYOHVGV79795644463Aug_aeoDDEjzoziisxoykuijhz"]'),
+	('{"": 1, "5abB58gXVQVTTMWU3jSHXMMNV": "", "nv": 934, "kjsnhtj": 8, "": [{"xm": [71, 425]}], "": -9}'),
+	('"__oliqCcbwwyqmtECsqivplcb1NTMOQRZTYRJONOIPWNHKWLJRIHKROMJNZLNGTTKRcedebccdbMTQXSzhynxmllqxuhnxBA_"'),
+	('["thgACBWGNGMkFFEA", [0, -1349, {"18": "RM", "F3": 6, "dP": "_AF"}, 64, 0, {"f": [8]}], 5, [[0]], 2]');
+INSERT INTO tbl (i, j, k) VALUES
+	(null,               null, null),
+	(null,               null, '[]'),
+	(null,               '[]', null),
+	(ARRAY[]::INTEGER[], null, null),
+	(null,               '[]', '[]'),
+	(ARRAY[]::INTEGER[], '[]', null),
+	(ARRAY[]::INTEGER[], '[]', '[]');
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+INSERT INTO tbl (i, j, k)
+	(SELECT gs.i, j.j, j.j || j.j
+	FROM jsondata j,
+	 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+	WHERE j.i = random(1,100)
+	);
+UPDATE tbl
+	SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+	WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+INSERT INTO tbl (i, j, k)
+	(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+	FROM jsondata x, jsondata y
+	WHERE x.i = random(1,100)
+	  AND y.i = random(1,100)
+	);
+SELECT gin_index_check('ginidx');
-- 
2.43.0

From 0e86a027ab785cb134d8cb5b8eee200b7c046569 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Mon, 16 Dec 2024 10:49:43 +0000
Subject: [PATCH v37 4/7] Fix for gin_index_check.

Never explicitly check high key on rightmost page is entry tree.
Its value is not stored explicitly and is equal to infitity.
Also never compare gin entries for different attnums.
---
 contrib/amcheck/verify_gin.c | 56 ++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 21 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 2dc5fbba619..ae3d24a8b86 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -163,6 +163,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 		Page		page;
 		OffsetNumber i,
 					maxoff;
+		BlockNumber rightlink;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -170,6 +171,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 									RBM_NORMAL, strategy);
 		LockBuffer(buffer, GIN_SHARE);
 		page = (Page) BufferGetPage(buffer);
+
 		Assert(GinPageIsData(page));
 
 		/* Check that the tree has the same height in all branches */
@@ -182,7 +184,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 
 			ItemPointerSetMin(&minItem);
 
-			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+			elog(DEBUG2, "page blk: %u, type leaf", stack->blkno);
 
 			if (leafdepth == -1)
 				leafdepth = stack->depth;
@@ -234,8 +236,8 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			 * Check that tuples in each page are properly ordered and
 			 * consistent with parent high key
 			 */
-			Assert(GinPageIsData(page));
 			maxoff = GinPageGetOpaque(page)->maxoff;
+			rightlink = GinPageGetOpaque(page)->rightlink;
 
 			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
 
@@ -273,7 +275,12 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 			 */
 			bound = *GinDataPageGetRightBound(page);
 
-			if (stack->parentblk != InvalidBlockNumber &&
+			/*
+			 * Gin page right bound has sane value if only not a highkey on
+			 * rightmost page on level.
+			 */
+			if (ItemPointerIsValid(&stack->parentkey) &&
+				rightlink != InvalidBlockNumber &&
 				!ItemPointerEquals(&stack->parentkey, &bound))
 				ereport(ERROR,
 						(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -287,11 +294,12 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 
 			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
 			{
+				GinPostingTreeScanItem *ptr;
 				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
 
 				/* ItemPointerGetOffsetNumber expects a valid pointer */
 				if (!(i == maxoff &&
-					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					  rightlink == InvalidBlockNumber))
 					elog(DEBUG3, "key (%u, %u) -> %u",
 						 ItemPointerGetBlockNumber(&posting_item->key),
 						 ItemPointerGetOffsetNumber(&posting_item->key),
@@ -300,8 +308,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 					elog(DEBUG3, "key (%u, %u) -> %u",
 						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
 
-				if (i == maxoff &&
-					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 				{
 					/*
 					 * The rightmost item in the tree level has (0, 0) as the
@@ -340,19 +347,23 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 									RelationGetRelationName(rel),
 									stack->blkno, i)));
 
-				/* If this is an internal page, recurse into the child */
-				if (!GinPageIsLeaf(page))
-				{
-					GinPostingTreeScanItem *ptr;
+				/* This is an internal page, recurse into the child */
+				ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+				ptr->depth = stack->depth + 1;
 
-					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
-					ptr->depth = stack->depth + 1;
+				/*
+				 * Set rightmost parent key to invalid iterm pointer. Its
+				 * value is 'Infinity' and not explicitly stored.
+				 */
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
 					ptr->parentkey = posting_item->key;
-					ptr->parentblk = stack->blkno;
-					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
-					ptr->next = stack->next;
-					stack->next = ptr;
-				}
+
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+				ptr->next = stack->next;
+				stack->next = ptr;
 			}
 		}
 		LockBuffer(buffer, GIN_UNLOCK);
@@ -411,7 +422,8 @@ gin_check_parent_keys_consistency(Relation rel,
 		Buffer		buffer;
 		Page		page;
 		OffsetNumber i,
-					maxoff;
+					maxoff,
+					prev_attnum;
 		XLogRecPtr	lsn;
 		IndexTuple	prev_tuple;
 		BlockNumber rightlink;
@@ -488,6 +500,7 @@ gin_check_parent_keys_consistency(Relation rel,
 		 * with parent high key
 		 */
 		prev_tuple = NULL;
+		prev_attnum = InvalidAttrNumber;
 		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
 		{
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
@@ -511,7 +524,7 @@ gin_check_parent_keys_consistency(Relation rel,
 			 * for high key on rightmost page, as this key is not really
 			 * stored explicitly.
 			 */
-			if (i != FirstOffsetNumber && stack->blkno != GIN_ROOT_BLKNO &&
+			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
 				!(i == maxoff && rightlink == InvalidBlockNumber))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
@@ -520,8 +533,8 @@ gin_check_parent_keys_consistency(Relation rel,
 									  current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
-							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u",
-									RelationGetRelationName(rel), stack->blkno, i)));
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
+									RelationGetRelationName(rel), stack->blkno, i, rightlink)));
 			}
 
 			/*
@@ -620,6 +633,7 @@ gin_check_parent_keys_consistency(Relation rel,
 			}
 
 			prev_tuple = CopyIndexTuple(idxtuple);
+			prev_attnum = attnum;
 		}
 
 		LockBuffer(buffer, GIN_UNLOCK);
-- 
2.43.0

From 4c13e172d5ddfbdac412f4247e3e049d075b7699 Mon Sep 17 00:00:00 2001
From: reshke kirill <reshke@double.cloud>
Date: Tue, 3 Dec 2024 15:02:47 +0000
Subject: [PATCH v37 3/7] Fix wording in GIN README.

---
 src/backend/access/gin/README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/gin/README b/src/backend/access/gin/README
index b0807316212..742bcbad499 100644
--- a/src/backend/access/gin/README
+++ b/src/backend/access/gin/README
@@ -237,10 +237,10 @@ GIN packs keys and downlinks into tuples in a different way.
 
 P_i is grouped with K_{i+1}.  -Inf key is not needed.
 
-There are couple of additional notes regarding K_{n+1} key.
-1) In entry tree rightmost page, a key coupled with P_n doesn't really matter.
+There are a couple of additional notes regarding K_{n+1} key.
+1) In the entry tree on the rightmost page, a key coupled with P_n doesn't really matter.
 Highkey is assumed to be infinity.
-2) In posting tree, a key coupled with P_n always doesn't matter.  Highkey for
+2) In the posting tree, a key coupled with P_n always doesn't matter.  Highkey for
 non-rightmost pages is stored separately and accessed via
 GinDataPageGetRightBound().
 
-- 
2.43.0

From 88a76cc81a2479f901e382d80cc83b60f9009b7e Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 09:27:00 -0800
Subject: [PATCH v37 2/7] Add gin_index_check() to verify GIN index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |  14 +
 contrib/amcheck/amcheck.control        |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   3 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 774 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  20 +
 8 files changed, 920 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..1b7a63cbaa4 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gin check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..445c48ccb7d
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 67a4ac8518d..b33e8c9b062 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'verify_common.c',
+  'verify_gin.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..2dc5fbba619
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,774 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ * Verification checks that all paths in GIN graph contain
+ * consistent keys: tuples on parent pages consistently include tuples
+ * from children pages. Also, verification checks graph invariants:
+ * internal page must have at least one downlinks, internal page can
+ * reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of GIN index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+}			GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of depth-first scan of GIN  posting tree.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+}			GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Allocates memory context and scans through postigTree graph
+ *
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[MAXPGPATH];
+
+			ItemPointerSetMin(&minItem);
+
+			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			Assert(GinPageIsData(page));
+			maxoff = GinPageGetOpaque(page)->maxoff;
+
+			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				/* ItemPointerGetOffsetNumber expects a valid pointer */
+				if (!(i == maxoff &&
+					  GinPageGetOpaque(page)->rightlink == InvalidBlockNumber))
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 ItemPointerGetBlockNumber(&posting_item->key),
+						 ItemPointerGetOffsetNumber(&posting_item->key),
+						 BlockIdGetBlockNumber(&posting_item->child_blkno));
+				else
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff &&
+					GinPageGetOpaque(page)->rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* If this is an internal page, recurse into the child */
+				if (!GinPageIsLeaf(page))
+				{
+					GinPostingTreeScanItem *ptr;
+
+					ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+					ptr->depth = stack->depth + 1;
+					ptr->parentkey = posting_item->key;
+					ptr->parentblk = stack->blkno;
+					ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+					ptr->next = stack->next;
+					stack->next = ptr;
+				}
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN check. Allocates memory context and scans through
+ * GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+		BlockNumber rightlink;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+		rightlink = GinPageGetOpaque(page)->rightlink;
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		elog(DEBUG3, "processing entry tree page at blk %u, maxoff: %u", stack->blkno, maxoff);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected for blk: %u, parent blk: %u", stack->blkno, stack->parentblk);
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/*
+			 * First block is metadata, skip order check. Also, never check
+			 * for high key on rightmost page, as this key is not really
+			 * stored explicitly.
+			 */
+			if (i != FirstOffsetNumber && stack->blkno != GIN_ROOT_BLKNO &&
+				!(i == maxoff && rightlink == InvalidBlockNumber))
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u",
+									RelationGetRelationName(rel), stack->blkno, i)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						 * Check if it is properly adjusted. If succeed,
+						 * procced to the next key.
+						 */
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index a12aa3abf01..98f836e15e7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,26 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
   </variablelist>
   <tip>
    <para>
-- 
2.43.0

From b9cc198a4daf14f1ee5242ed7413be90bda18094 Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 09:18:04 -0800
Subject: [PATCH v37 1/7] Refactor amcheck internals to isolate common locking
 and checking routines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before doing checks, other indexes must take the same safety measures:
 - Making sure the index can be checked
 - changing the context of the user
 - keeping track of GUCs modified via index functions
This contribution relocates the existing functionality to amcheck.c for reuse.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 6 files changed, 296 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 61d7eaf2305..67a4ac8518d 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2025, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'verify_common.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..c8ed685ba42
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_common.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2024, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_common.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..30994e22933
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2017-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 7543be17552..9dc76f0e5d4 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -156,14 +157,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * Check arguments
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+}			BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -238,15 +247,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -264,18 +279,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -284,193 +304,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
-- 
2.43.0

From 3a5161bd1125a0a4e4e449501a1c02e6e8f7cc42 Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 09:40:37 -0800
Subject: [PATCH v37 5/7] Add gin index checking test for jsonb data

Extend the previously committed test of gin index checking to also
include a table using jsonb_path_ops.
---
 contrib/amcheck/expected/check_gin.out | 14 ++++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 12 ++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index bbcde80e627..93147de0ef1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -62,3 +62,17 @@ SELECT gin_index_check('gin_check_text_array_idx');
 
 -- cleanup
 DROP TABLE gin_check_text_array;
+-- Test GIN over jsonb
+CREATE TABLE "gin_check_jsonb"("j" jsonb);
+INSERT INTO gin_check_jsonb values ('{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
+INSERT INTO gin_check_jsonb values ('[[14,2,3]]');
+INSERT INTO gin_check_jsonb values ('[1,[14,2,3]]');
+CREATE INDEX "gin_check_jsonb_idx" on gin_check_jsonb USING GIN("j" jsonb_path_ops);
+SELECT gin_index_check('gin_check_jsonb_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_jsonb;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index bbd9b9f8281..92ddbbc7a89 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -38,3 +38,15 @@ SELECT gin_index_check('gin_check_text_array_idx');
 
 -- cleanup
 DROP TABLE gin_check_text_array;
+
+-- Test GIN over jsonb
+CREATE TABLE "gin_check_jsonb"("j" jsonb);
+INSERT INTO gin_check_jsonb values ('{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
+INSERT INTO gin_check_jsonb values ('[[14,2,3]]');
+INSERT INTO gin_check_jsonb values ('[1,[14,2,3]]');
+CREATE INDEX "gin_check_jsonb_idx" on gin_check_jsonb USING GIN("j" jsonb_path_ops);
+
+SELECT gin_index_check('gin_check_jsonb_idx');
+
+-- cleanup
+DROP TABLE gin_check_jsonb;
-- 
2.43.0

From 84abfcbd7afcb77f19a24cd83438a10d7355cec0 Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 12:10:26 -0800
Subject: [PATCH v37 6/7] Add gin to the create index concurrently tap tests

These tests are already checking btree, and can cheaply be extended
to also check gin, so do that.
---
 contrib/amcheck/t/002_cic.pl     | 10 +++++---
 contrib/amcheck/t/003_cic_2pc.pl | 40 ++++++++++++++++++++++++++------
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
index 0b6a5a9e464..6a0c4f61125 100644
--- a/contrib/amcheck/t/002_cic.pl
+++ b/contrib/amcheck/t/002_cic.pl
@@ -21,8 +21,9 @@ $node->append_conf('postgresql.conf',
 	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
 $node->start;
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
-$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 $node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i)));
+$node->safe_psql('postgres', q(CREATE INDEX ginidx ON tbl USING gin(j)));
 
 #
 # Stress CIC with pgbench.
@@ -40,13 +41,13 @@ $node->pgbench(
 	{
 		'002_pgbench_concurrent_transaction' => q(
 			BEGIN;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0, '{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
 			COMMIT;
 		  ),
 		'002_pgbench_concurrent_transaction_savepoints' => q(
 			BEGIN;
 			SAVEPOINT s1;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 			COMMIT;
 		  ),
 		'002_pgbench_concurrent_cic' => q(
@@ -54,7 +55,10 @@ $node->pgbench(
 			\if :gotlock
 				DROP INDEX CONCURRENTLY idx;
 				CREATE INDEX CONCURRENTLY idx ON tbl(i);
+				DROP INDEX CONCURRENTLY ginidx;
+				CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 				SELECT bt_index_check('idx',true);
+				SELECT gin_index_check('ginidx');
 				SELECT pg_advisory_unlock(42);
 			\endif
 		  )
diff --git a/contrib/amcheck/t/003_cic_2pc.pl b/contrib/amcheck/t/003_cic_2pc.pl
index 9134487f3b4..00a446a381f 100644
--- a/contrib/amcheck/t/003_cic_2pc.pl
+++ b/contrib/amcheck/t/003_cic_2pc.pl
@@ -25,7 +25,7 @@ $node->append_conf('postgresql.conf',
 	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
 $node->start;
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
-$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 
 
 #
@@ -41,7 +41,7 @@ my $main_h = $node->background_psql('postgres');
 $main_h->query_safe(
 	q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
 my $cic_h = $node->background_psql('postgres');
@@ -50,6 +50,7 @@ $cic_h->query_until(
 	qr/start/, q(
 \echo start
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $main_h->query_safe(
@@ -60,7 +61,7 @@ PREPARE TRANSACTION 'a';
 $main_h->query_safe(
 	q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'a';));
@@ -69,7 +70,7 @@ $main_h->query_safe(
 	q(
 PREPARE TRANSACTION 'b';
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '"mary had a little lamb"');
 ));
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'b';));
@@ -86,6 +87,9 @@ $cic_h->quit;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after overlapping 2PC');
 
+$result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
+is($result, '0', 'gin_index_check after overlapping 2PC');
+
 
 #
 # Server restart shall not change whether prepared xact blocks CIC
@@ -94,7 +98,7 @@ is($result, '0', 'bt_index_check after overlapping 2PC');
 $node->safe_psql(
 	'postgres', q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
 PREPARE TRANSACTION 'spans_restart';
 BEGIN;
 CREATE TABLE unused ();
@@ -108,12 +112,16 @@ $reindex_h->query_until(
 \echo start
 DROP INDEX CONCURRENTLY idx;
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
+DROP INDEX CONCURRENTLY ginidx;
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $node->safe_psql('postgres', "COMMIT PREPARED 'spans_restart'");
 $reindex_h->quit;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after 2PC and restart');
+$result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
+is($result, '0', 'gin_index_check after 2PC and restart');
 
 
 #
@@ -136,14 +144,14 @@ $node->pgbench(
 	{
 		'003_pgbench_concurrent_2pc' => q(
 			BEGIN;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0,'null');
 			PREPARE TRANSACTION 'c:client_id';
 			COMMIT PREPARED 'c:client_id';
 		  ),
 		'003_pgbench_concurrent_2pc_savepoint' => q(
 			BEGIN;
 			SAVEPOINT s1;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0,'[false, "jnvaba", -76, 7, {"_": [1]}, 9]');
 			PREPARE TRANSACTION 'c:client_id';
 			COMMIT PREPARED 'c:client_id';
 		  ),
@@ -163,7 +171,25 @@ $node->pgbench(
 				SELECT bt_index_check('idx',true);
 				SELECT pg_advisory_unlock(42);
 			\endif
+		  ),
+		'005_pgbench_concurrent_cic' => q(
+			SELECT pg_try_advisory_lock(42)::integer AS gotginlock \gset
+			\if :gotginlock
+				DROP INDEX CONCURRENTLY ginidx;
+				CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
+				SELECT gin_index_check('ginidx');
+				SELECT pg_advisory_unlock(42);
+			\endif
+		  ),
+		'006_pgbench_concurrent_ric' => q(
+			SELECT pg_try_advisory_lock(42)::integer AS gotginlock \gset
+			\if :gotginlock
+				REINDEX INDEX CONCURRENTLY ginidx;
+				SELECT gin_index_check('ginidx');
+				SELECT pg_advisory_unlock(42);
+			\endif
 		  )
+
 	});
 
 $node->stop;
-- 
2.43.0

From 8682c4b200b32b38eb74b9cdd45d5995fb1f79ee Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 12:11:07 -0800
Subject: [PATCH v37 7/7] Stress test verify_gin() using pgbench

Add a tap test which inserts, updates, deletes, and checks in
parallel.  Like all pgbench based tap tests, this test contains race
conditions between the operations, so Your Mileage May Vary.  For
me, on my laptop, I got failures like:

	index "ginidx" has wrong tuple order on entry tree page

which I have not yet investigated.  The test is included here for
anybody interested in debugging this failure.
---
 contrib/amcheck/t/006_gin_concurrency.pl | 196 +++++++++++++++++++++++
 1 file changed, 196 insertions(+)
 create mode 100644 contrib/amcheck/t/006_gin_concurrency.pl

diff --git a/contrib/amcheck/t/006_gin_concurrency.pl b/contrib/amcheck/t/006_gin_concurrency.pl
new file mode 100644
index 00000000000..afc67940d4d
--- /dev/null
+++ b/contrib/amcheck/t/006_gin_concurrency.pl
@@ -0,0 +1,196 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i integer[], j jsonb, k jsonb)));
+$node->safe_psql('postgres', q(CREATE INDEX ginidx ON tbl USING gin(i, j, k)));
+$node->safe_psql('postgres', q(CREATE TABLE jsondata (i serial, j jsonb)));
+$node->safe_psql('postgres', q(INSERT INTO jsondata (j) VALUES
+	('1'),
+	('91'),
+	('[5]'),
+	('true'),
+	('"zxI"'),
+	('[1, 7]'),
+	('["", 4]'),
+	('"utDFBz"'),
+	('[[9], ""]'),
+	('"eCvxKPML"'),
+	('["1VMQNQM"]'),
+	('{"": "562c"}'),
+	('[58, 8, null]'),
+	('{"": {"": 62}}'),
+	('["", 6, 19, ""]'),
+	('{"ddfWTQ": true}'),
+	('["", 734.2, 9, 5]'),
+	('"GMV27mjtuuqmlltw"'),
+	('{"dabe": -5, "": 6}'),
+	('"hgihykirQGIYTcCA30"'),
+	('[9, {"Utrn": -6}, ""]'),
+	('"BJTZUMST1_WWEgyqgka_"'),
+	('["", -4, "", [-2], -47]'),
+	('{"": [3], "": {"": "y"}}'),
+	('{"myuijj": "YUWIUZXXLGS"}'),
+	('{"3": false, "C": "1sHTX"}'),
+	('"ZGUORVDE_ACF1QXJ_hipgwrks"'),
+	('{"072": [3, -4], "oh": "eL"}'),
+	('[{"de": 9, "JWHPMRZJW": [0]}]'),
+	('"EACJUZEBAFFBEE6706SZLWVGO635"'),
+	('["P", {"TZW": [""]}, {"": [0]}]'),
+	('{"": -6, "YMb": -22, "__": [""]}'),
+	('{"659": [8], "bfc": [0], "V": ""}'),
+	('{"8776": "1tryl", "Q": 2, "": 4.6}'),
+	('[[1], "", 9, 0, [1, 0], -1, 0, "C"]'),
+	('"635321pnpjlfFzhGTIYP9265iA_19D8260"'),
+	('"klmxsoCFDtzxrhotsqlnmvmzlcbdde34twj"'),
+	('"GZSXSZVS19ecbe_ZJJED0379c1j9_GSU9167"'),
+	('{"F18s": {"": -84194}, "ececab2": [""]}'),
+	('["", {"SVAvgg": "Q"}, 1, 9, "gypy", [1]]'),
+	('[[""], {"": 5}, "GVZGGVGSWM", 2, ["", 8]]'),
+	('{"V": 8, "TPNL": [826, null], "4": -9.729}'),
+	('{"HTJP_DAptxn6": 9, "": "r", "hji4124": ""}'),
+	('[1, ["9", 5, 6, ""], {"": "", "": "efb"}, 7]'),
+	('{"": 6, "1251e_cajrgkyzuxBEDM017444EFD": 548}'),
+	('{"853": -60, "TGLUG_jxmrggv": null, "pjx": ""}'),
+	('[0, "wsgnnvCfJVV_KOMLVXOUIS9FIQLPXXBbbaohjrpj"]'),
+	('"nizvkl36908OLW22ecbdeEBMHMiCEEACcikwkjpmu30X_m"'),
+	('{"bD24eeVZWY": 1, "Bt": 9, "": 6052, "FT": ["h"]}'),
+	('"CDBnouyzlAMSHJCtguxxizpzgkNYfaNLURVITNLYVPSNLYNy"'),
+	('{"d": [[4, "N"], null, 6, true], "1PKV": 6, "9": 6}'),
+	('[-7326, [83, 55], -63, [0, {"": 1}], {"ri0": false}]'),
+	('{"": 117.38, "FCkx3608szztpvjolomzvlyrshyvrgz": -4.2}'),
+	('["", 8, {"WXHNG": {"6": 4}}, [null], 7, 2, "", 299, 6]'),
+	('[[-992.2, "TPm", "", "cedeff79BD8", "t", [1]], 0, [-7]]'),
+	('[9, 34, ["LONuyiYGQZ"], [7, 88], ["c"], 1, 6, "", [[2]]]'),
+	('[20, 5, null, "eLHTXRWNV", 8, ["pnpvrum", -3], "FINY", 3]'),
+	('[{"": "", "b": 2, "d": "egu"}, "aPNK", 2, 9, {"": -79946}]'),
+	('[1, {"769": 9}, 5, 9821, 22, 0, 2.7, 5, 4, 191, 54.599, 24]'),
+	('["c", 77, "b_0lplvHJNLMxw", "VN76dhFadaafadfe5dfbco", false]'),
+	('"TYIHXebbPK_86QMP_199bEEIS__8205986vdC_CFAEFBFCEFCJQRHYoqztv"'),
+	('"cdmxxxzrhtxpwuyrxinmhb5577NSPHIHMTPQYTXSUVVGJPUUMCBEDb_1569e"'),
+	('[[5, null, "C"], "ORNR", "mnCb", 1, -800, "6953", ["K", 0], ""]'),
+	('"SSKLTHJxjxywwquhiwsde353eCIJJjkyvn9946c2cdVadcboiyZFAYMHJWGMMT"'),
+	('"5185__D5AtvhizvmEVceF3jxtghlCF0789_owmsztJHRMOJ7rlowxqq51XLXJbF"'),
+	('{"D": 565206, "xupqtmfedff": "ZGJN9", "9": 1, "glzv": -47, "": -8}'),
+	('{"": 9, "": {"": [null], "ROP": 842}, "": ["5FFD", 7, 5, 1, 94, 1]}'),
+	('{"JLn": ["8s"], "": "_ahxizrzhivyzvhr", "XSAt": 5, "P": 2838, "": 5}'),
+	('[51, 3, {"": 9, "": -9, "": [[6]]}, 7, 7, {"": 0}, "TXLQL", 7.6, [7]]'),
+	('[-38.7, "kre40", 5, {"": null}, "tvuv", 8, "", "", "uizygprwwvh", "1"]'),
+	('"z934377_nxmzjnuqglgyukjteefeihjyot1irkvwnnrqinptlpzwjgmkjbQMUVxxwvbdz"'),
+	('[165.9, "dAFD_60JQPYbafh", false, {"": 6, "": "fcfd"}, [[2], "c"], 4, 2]'),
+	('"ffHOOPVSSACDqiyeecTNWJMWPNRXU283aHRXNUNZZZQPUGYSQTTQXQVJM5eeafcIPGIHcac"'),
+	('[2, 8, -53, {"": 5}, "F9", 8, "SGUJPNVI", "7OLOZH", 9.84, {"": 6}, 207, 6]'),
+	('"xqmqmyljhq__ZGWJVNefagsxrsktruhmlinhxloupuVQW0804901NKGGMNNSYYXWQOosz8938"'),
+	('{"FEoLfaab1160167": {"L": [42, 0]}, "938": "FCCUPGYYYMQSQVZJKM", "knqmk": 2}'),
+	('"0igyurmOMSXIYHSZQEAcxlvgqdxkhwtrbaabfaaMC138Z_BDRLrythpi30_MPRXMTOILRLswmoy"'),
+	('"1129BBCABFFAACA9VGVKipnwohaccc9TSIMTOQKHmcGYVeFE_PWKLHmpyj60137672qugtsstugg"'),
+	('"D3BDA069074174vx48A37IVHWVXLUP9382542ypsl1465pixtryzCBgrkkhrvCC_BDDFatkyXHLIe"'),
+	('[{"esx7": -53, "ec60834YGVMYoXAAvgxmmqnojyzmiklhdovFipl": 2, "os": 66433}, 9.13]'),
+	('{"": ["", 4, null, 5, null], "": "3", "5_GMMHTIhPB_F_vsebc1": "Er", "GY": 121.32}'),
+	('["krTVPYDEd", 5, 8, [6, -6], [[-9], 3340, [[""]]], "", 5, [6, true], 3, "", 1, ""]'),
+	('{"rBNPKN8446080wruOLeceaCBDCKWNUYYMONSJUlCDFExr": {"": "EE0", "6826": 5, "": 7496}}'),
+	('[3, {"": -8}, "101dboMVSNKZLVPITLHLPorwwuxxjmjsh", "", "LSQPRVYKWVYK945imrh", 4, 51]'),
+	('[["HY6"], "", "bcdB", [2, [85, 1], 3, 3, 3, [8]], "", ["_m"], "2", -33, 8, 3, "_xwj"]'),
+	('["", 0, -3.7, 8, false, null, {"": 5}, 9, "06FccxFcdb283bbZGGVRSMWLJH2_PBAFpwtkbceto"]'),
+	('[52, "", -39, -7, [1], "c", {"": 9, "": 45528, "G": {"": 7}}, 3, false, 0, "EB", 8, -6]'),
+	('"qzrkvrlG78CCCEBCptzwwok808805243QXVSYed3efZSKLSNXPxhrS357KJMWSKgrfcFFDFDWKSXJJSIJ_yqJu"'),
+	('[43, 8, {"": ""}, "uwtv__HURKGJLGGPPW", 9, 66, "yqrvghxuw", {"J": false}, false, 2, 0, 4]'),
+	('[{"UVL": 7, "": 1}, false, [6, "H"], "boxlgqgm", 3, "znhm", [true], 0, ["e", 3.7], 9, 9.4]'),
+	('{"825634870117somzqw": 1, "": [5], "gYH": "_XT", "b22412631709RZP": 3, "": "", "FDB": [""]}'),
+	('[8, ["_bae"], "", "WN", 80, {"o": 2, "aff": 16}, false, true, 4, 6, {"nutzkzikolsxZRQ": 30}]'),
+	('["588BD9c_xzsn", {"k": 0, "_Ecezlkslrwvjpwrukiqzl": 3, "Ej": "4"}, "TUXwghn1dTNRXJZpswmD", 5]'),
+	('[{"dC": 7}, {"": 1, "4": 41, "": "", "": "adKS"}, {"": "ypv"}, 6, 9, 2, [-61.46], [1, 3.9], 2]'),
+	('{"8": 8, "": -364, "855": -238.1, "zj": 9, "SNHJG413": 3, "UMNVI73": [60, 0], "iwvqse": -1.833}'),
+	('"VTUKMLZKQPHIEniCFZ_cjrhvspxzulvxhqykjzmrw89OGOGISWdcrvpOPLOFALGK809896999xzqnkm63254_xrmcfcedb"'),
+	('["", "USNQbcexyFDCdBAFWJIphloxwytplyZZR008400FmoiYXVYOHVGV79795644463Aug_aeoDDEjzoziisxoykuijhz"]'),
+	('{"": 1, "5abB58gXVQVTTMWU3jSHXMMNV": "", "nv": 934, "kjsnhtj": 8, "": [{"xm": [71, 425]}], "": -9}'),
+	('"__oliqCcbwwyqmtECsqivplcb1NTMOQRZTYRJONOIPWNHKWLJRIHKROMJNZLNGTTKRcedebccdbMTQXSzhynxmllqxuhnxBA_"'),
+	('["thgACBWGNGMkFFEA", [0, -1349, {"18": "RM", "F3": 6, "dP": "_AF"}, 64, 0, {"f": [8]}], 5, [[0]], 2]')
+));
+
+#
+# Stress gin with pgbench.
+#
+# Modify the table data, and hence the index data, from multiple process
+# while from other processes run the index checking code.  This should,
+# if the index is large enough, result in the checks performing across
+# concurrent page splits.
+#
+$node->pgbench(
+	'--no-vacuum --client=20 --transactions=5000',
+	0,
+	[qr{actually processed}],
+	[qr{^$}],
+	'concurrent DML and index checking',
+	{
+		'006_gin_concurrency_insert_1' => q(
+			INSERT INTO tbl (i, j, k)
+				(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+					FROM jsondata x, jsondata y
+					WHERE x.i = random(1,100)
+					  AND y.i = random(1,100)
+				)
+		  ),
+		'006_gin_concurrency_insert_2' => q(
+			INSERT INTO tbl (i, j, k)
+				(SELECT gs.i, j.j, j.j || j.j
+					FROM jsondata j,
+						 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+					WHERE j.i = random(1,100)
+				)
+		  ),
+		'006_gin_concurrency_insert_nulls' => q(
+			INSERT INTO tbl (i, j, k) VALUES
+				(null,               null, null),
+				(null,               null, '[]'),
+				(null,               '[]', null),
+				(ARRAY[]::INTEGER[], null, null),
+				(null,               '[]', '[]'),
+				(ARRAY[]::INTEGER[], '[]', null),
+				(ARRAY[]::INTEGER[], '[]', '[]')
+		  ),
+		'006_gin_concurrency_update_i' => q(
+			UPDATE tbl
+				SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+				WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_update_j' => q(
+			UPDATE tbl
+				SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+				WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_update_k' => q(
+			UPDATE tbl
+				SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+				WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_delete' => q(
+			DELETE FROM tbl
+				WHERE random(1,5) = 3;
+		),
+		'006_gin_concurrency_gin_index_check' => q(
+				SELECT gin_index_check('ginidx');
+		)
+	});
+
+$node->stop;
+done_testing();
+
-- 
2.43.0

From 28b392b687f641b09bc79bb3bb3e61505845e6c1 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Fri, 28 Mar 2025 16:49:04 +0100
Subject: [PATCH v20250328 1/6] Fix grammar in GIN README

Author: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://postgr.es/m/CALdSSPgu9uAhVYojQ0yjG%3Dq5MaqmiSLUJPhz%2B-u7cA6K6Mc9UA%40mail.gmail.com
---
 src/backend/access/gin/README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/gin/README b/src/backend/access/gin/README
index b0807316212..742bcbad499 100644
--- a/src/backend/access/gin/README
+++ b/src/backend/access/gin/README
@@ -237,10 +237,10 @@ GIN packs keys and downlinks into tuples in a different way.
 
 P_i is grouped with K_{i+1}.  -Inf key is not needed.
 
-There are couple of additional notes regarding K_{n+1} key.
-1) In entry tree rightmost page, a key coupled with P_n doesn't really matter.
+There are a couple of additional notes regarding K_{n+1} key.
+1) In the entry tree on the rightmost page, a key coupled with P_n doesn't really matter.
 Highkey is assumed to be infinity.
-2) In posting tree, a key coupled with P_n always doesn't matter.  Highkey for
+2) In the posting tree, a key coupled with P_n always doesn't matter.  Highkey for
 non-rightmost pages is stored separately and accessed via
 GinDataPageGetRightBound().
 
-- 
2.49.0

From 40288f3d42b2e8ca716333826e5b67cec5fa7b3d Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Fri, 28 Mar 2025 15:40:09 +0100
Subject: [PATCH v20250328 2/6] amcheck: Move common routines into a separate
 module
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Before performing checks on an index, we need to take some safety
measures that apply to all index AMs. This includes:

* verifying that the index can be checked - Only selected AMs are
supported by amcheck (right now only B-Tree). The index has to be
valid and not a temporary index from another session.

* changing (and then restoring) user's security context

* obtaining proper locks on the index (and table, if needed)

* discarding GUC changes from the index functions

Until now this was implemented in the B-Tree amcheck module, but it's
something every AM will have to do. So relocate the code into a new
module verify_common for reuse.

The shared steps are implemented by amcheck_lock_relation_and_check(),
receiving the AM-specific verification as a callback. Custom parameters
may be supplied using a pointer.

Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas@vondra.me>
Reviewed-By: Mark Dilger <mark.dilger@enterprisedb.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile                 |   1 +
 contrib/amcheck/expected/check_btree.out |   4 +-
 contrib/amcheck/meson.build              |   1 +
 contrib/amcheck/verify_common.c          | 191 ++++++++++++++++
 contrib/amcheck/verify_common.h          |  31 +++
 contrib/amcheck/verify_nbtree.c          | 267 ++++++-----------------
 src/tools/pgindent/typedefs.list         |   1 +
 7 files changed, 297 insertions(+), 199 deletions(-)
 create mode 100644 contrib/amcheck/verify_common.c
 create mode 100644 contrib/amcheck/verify_common.h

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index 5e9002d2501..c3d70f3369c 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -3,6 +3,7 @@
 MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
+	verify_common.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
diff --git a/contrib/amcheck/expected/check_btree.out b/contrib/amcheck/expected/check_btree.out
index e7fb5f55157..c6f4b16c556 100644
--- a/contrib/amcheck/expected/check_btree.out
+++ b/contrib/amcheck/expected/check_btree.out
@@ -57,8 +57,8 @@ ERROR:  could not open relation with OID 17
 BEGIN;
 CREATE INDEX bttest_a_brin_idx ON bttest_a USING brin(id);
 SELECT bt_index_parent_check('bttest_a_brin_idx');
-ERROR:  only B-Tree indexes are supported as targets for verification
-DETAIL:  Relation "bttest_a_brin_idx" is not a B-Tree index.
+ERROR:  expected "btree" index as targets for verification
+DETAIL:  Relation "bttest_a_brin_idx" is a brin index.
 ROLLBACK;
 -- normal check outside of xact
 SELECT bt_index_check('bttest_a_idx');
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 61d7eaf2305..67a4ac8518d 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -1,6 +1,7 @@
 # Copyright (c) 2022-2025, PostgreSQL Global Development Group
 
 amcheck_sources = files(
+  'verify_common.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
diff --git a/contrib/amcheck/verify_common.c b/contrib/amcheck/verify_common.c
new file mode 100644
index 00000000000..d095e62ce55
--- /dev/null
+++ b/contrib/amcheck/verify_common.c
@@ -0,0 +1,191 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_common.c
+ *		Utility functions common to all access methods.
+ *
+ * Copyright (c) 2016-2025, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_common.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/table.h"
+#include "access/tableam.h"
+#include "verify_common.h"
+#include "catalog/index.h"
+#include "catalog/pg_am.h"
+#include "commands/tablecmds.h"
+#include "utils/guc.h"
+#include "utils/syscache.h"
+
+static bool amcheck_index_mainfork_expected(Relation rel);
+
+
+/*
+ * Check if index relation should have a file for its main relation fork.
+ * Verification uses this to skip unlogged indexes when in hot standby mode,
+ * where there is simply nothing to verify.
+ *
+ * NB: Caller should call index_checkable() before calling here.
+ */
+static bool
+amcheck_index_mainfork_expected(Relation rel)
+{
+	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
+		!RecoveryInProgress())
+		return true;
+
+	ereport(NOTICE,
+			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
+			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
+					RelationGetRelationName(rel))));
+
+	return false;
+}
+
+/*
+* Amcheck main workhorse.
+* Given index relation OID, lock relation.
+* Next, take a number of standard actions:
+* 1) Make sure the index can be checked
+* 2) change the context of the user,
+* 3) keep track of GUCs modified via index functions
+* 4) execute callback function to verify integrity.
+*/
+void
+amcheck_lock_relation_and_check(Oid indrelid,
+								Oid am_id,
+								IndexDoCheckCallback check,
+								LOCKMODE lockmode,
+								void *state)
+{
+	Oid			heapid;
+	Relation	indrel;
+	Relation	heaprel;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+
+	/*
+	 * We must lock table before index to avoid deadlocks.  However, if the
+	 * passed indrelid isn't an index then IndexGetRelation() will fail.
+	 * Rather than emitting a not-very-helpful error message, postpone
+	 * complaining, expecting that the is-it-an-index test below will fail.
+	 *
+	 * In hot standby mode this will raise an error when parentcheck is true.
+	 */
+	heapid = IndexGetRelation(indrelid, true);
+	if (OidIsValid(heapid))
+	{
+		heaprel = table_open(heapid, lockmode);
+
+		/*
+		 * Switch to the table owner's userid, so that any index functions are
+		 * run as that user.  Also lock down security-restricted operations
+		 * and arrange to make GUC variable changes local to this command.
+		 */
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+	else
+	{
+		heaprel = NULL;
+		/* Set these just to suppress "uninitialized variable" warnings */
+		save_userid = InvalidOid;
+		save_sec_context = -1;
+		save_nestlevel = -1;
+	}
+
+	/*
+	 * Open the target index relations separately (like relation_openrv(), but
+	 * with heap relation locked first to prevent deadlocking).  In hot
+	 * standby mode this will raise an error when parentcheck is true.
+	 *
+	 * There is no need for the usual indcheckxmin usability horizon test
+	 * here, even in the heapallindexed case, because index undergoing
+	 * verification only needs to have entries for a new transaction snapshot.
+	 * (If this is a parentcheck verification, there is no question about
+	 * committed or recently dead heap tuples lacking index entries due to
+	 * concurrent activity.)
+	 */
+	indrel = index_open(indrelid, lockmode);
+
+	/*
+	 * Since we did the IndexGetRelation call above without any lock, it's
+	 * barely possible that a race against an index drop/recreation could have
+	 * netted us the wrong table.
+	 */
+	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_TABLE),
+				 errmsg("could not open parent table of index \"%s\"",
+						RelationGetRelationName(indrel))));
+
+	/* Check that relation suitable for checking */
+	if (index_checkable(indrel, am_id))
+		check(indrel, heaprel, state, lockmode == ShareLock);
+
+	/* Roll back any GUC changes executed by index functions */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	/*
+	 * Release locks early. That's ok here because nothing in the called
+	 * routines will trigger shared cache invalidations to be sent, so we can
+	 * relax the usual pattern of only releasing locks after commit.
+	 */
+	index_close(indrel, lockmode);
+	if (heaprel)
+		table_close(heaprel, lockmode);
+}
+
+/*
+ * Basic checks about the suitability of a relation for checking as an index.
+ *
+ *
+ * NB: Intentionally not checking permissions, the function is normally not
+ * callable by non-superusers. If granted, it's useful to be able to check a
+ * whole cluster.
+ */
+bool
+index_checkable(Relation rel, Oid am_id)
+{
+	if (rel->rd_rel->relkind != RELKIND_INDEX ||
+		rel->rd_rel->relam != am_id)
+	{
+		HeapTuple	amtup;
+		HeapTuple	amtuprel;
+
+		amtup = SearchSysCache1(AMOID, ObjectIdGetDatum(am_id));
+		amtuprel = SearchSysCache1(AMOID, ObjectIdGetDatum(rel->rd_rel->relam));
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("expected \"%s\" index as targets for verification", NameStr(((Form_pg_am) GETSTRUCT(amtup))->amname)),
+				 errdetail("Relation \"%s\" is a %s index.",
+						   RelationGetRelationName(rel), NameStr(((Form_pg_am) GETSTRUCT(amtuprel))->amname))));
+	}
+
+	if (RELATION_IS_OTHER_TEMP(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot access temporary tables of other sessions"),
+				 errdetail("Index \"%s\" is associated with temporary relation.",
+						   RelationGetRelationName(rel))));
+
+	if (!rel->rd_index->indisvalid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot check index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail("Index is not valid.")));
+
+	return amcheck_index_mainfork_expected(rel);
+}
diff --git a/contrib/amcheck/verify_common.h b/contrib/amcheck/verify_common.h
new file mode 100644
index 00000000000..b2565bfbbab
--- /dev/null
+++ b/contrib/amcheck/verify_common.h
@@ -0,0 +1,31 @@
+/*-------------------------------------------------------------------------
+ *
+ * amcheck.h
+ *		Shared routines for amcheck verifications.
+ *
+ * Copyright (c) 2016-2025, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/amcheck.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "storage/bufpage.h"
+#include "storage/lmgr.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "miscadmin.h"
+
+/* Typedefs for callback functions for amcheck_lock_relation */
+typedef void (*IndexCheckableCallback) (Relation index);
+typedef void (*IndexDoCheckCallback) (Relation rel,
+									  Relation heaprel,
+									  void *state,
+									  bool readonly);
+
+extern void amcheck_lock_relation_and_check(Oid indrelid,
+											Oid am_id,
+											IndexDoCheckCallback check,
+											LOCKMODE lockmode, void *state);
+
+extern bool index_checkable(Relation rel, Oid am_id);
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index d56eb7637d3..f11c43a0ed7 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -30,6 +30,7 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "verify_common.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_opfamily_d.h"
@@ -159,14 +160,22 @@ typedef struct BtreeLastVisibleEntry
 	ItemPointer tid;			/* Heap tid */
 } BtreeLastVisibleEntry;
 
+/*
+ * arguments for the bt_index_check_callback callback
+ */
+typedef struct BTCallbackState
+{
+	bool		parentcheck;
+	bool		heapallindexed;
+	bool		rootdescend;
+	bool		checkunique;
+} BTCallbackState;
+
 PG_FUNCTION_INFO_V1(bt_index_check);
 PG_FUNCTION_INFO_V1(bt_index_parent_check);
 
-static void bt_index_check_internal(Oid indrelid, bool parentcheck,
-									bool heapallindexed, bool rootdescend,
-									bool checkunique);
-static inline void btree_index_checkable(Relation rel);
-static inline bool btree_index_mainfork_expected(Relation rel);
+static void bt_index_check_callback(Relation indrel, Relation heaprel,
+									void *state, bool readonly);
 static void bt_check_every_level(Relation rel, Relation heaprel,
 								 bool heapkeyspace, bool readonly, bool heapallindexed,
 								 bool rootdescend, bool checkunique);
@@ -241,15 +250,21 @@ Datum
 bt_index_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = false;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
-	if (PG_NARGS() == 3)
-		checkunique = PG_GETARG_BOOL(2);
+		args.heapallindexed = PG_GETARG_BOOL(1);
+	if (PG_NARGS() >= 3)
+		args.checkunique = PG_GETARG_BOOL(2);
 
-	bt_index_check_internal(indrelid, false, heapallindexed, false, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									AccessShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -267,18 +282,23 @@ Datum
 bt_index_parent_check(PG_FUNCTION_ARGS)
 {
 	Oid			indrelid = PG_GETARG_OID(0);
-	bool		heapallindexed = false;
-	bool		rootdescend = false;
-	bool		checkunique = false;
+	BTCallbackState args;
+
+	args.heapallindexed = false;
+	args.rootdescend = false;
+	args.parentcheck = true;
+	args.checkunique = false;
 
 	if (PG_NARGS() >= 2)
-		heapallindexed = PG_GETARG_BOOL(1);
+		args.heapallindexed = PG_GETARG_BOOL(1);
 	if (PG_NARGS() >= 3)
-		rootdescend = PG_GETARG_BOOL(2);
-	if (PG_NARGS() == 4)
-		checkunique = PG_GETARG_BOOL(3);
+		args.rootdescend = PG_GETARG_BOOL(2);
+	if (PG_NARGS() >= 4)
+		args.checkunique = PG_GETARG_BOOL(3);
 
-	bt_index_check_internal(indrelid, true, heapallindexed, rootdescend, checkunique);
+	amcheck_lock_relation_and_check(indrelid, BTREE_AM_OID,
+									bt_index_check_callback,
+									ShareLock, &args);
 
 	PG_RETURN_VOID();
 }
@@ -287,193 +307,46 @@ bt_index_parent_check(PG_FUNCTION_ARGS)
  * Helper for bt_index_[parent_]check, coordinating the bulk of the work.
  */
 static void
-bt_index_check_internal(Oid indrelid, bool parentcheck, bool heapallindexed,
-						bool rootdescend, bool checkunique)
+bt_index_check_callback(Relation indrel, Relation heaprel, void *state, bool readonly)
 {
-	Oid			heapid;
-	Relation	indrel;
-	Relation	heaprel;
-	LOCKMODE	lockmode;
-	Oid			save_userid;
-	int			save_sec_context;
-	int			save_nestlevel;
-
-	if (parentcheck)
-		lockmode = ShareLock;
-	else
-		lockmode = AccessShareLock;
-
-	/*
-	 * We must lock table before index to avoid deadlocks.  However, if the
-	 * passed indrelid isn't an index then IndexGetRelation() will fail.
-	 * Rather than emitting a not-very-helpful error message, postpone
-	 * complaining, expecting that the is-it-an-index test below will fail.
-	 *
-	 * In hot standby mode this will raise an error when parentcheck is true.
-	 */
-	heapid = IndexGetRelation(indrelid, true);
-	if (OidIsValid(heapid))
-	{
-		heaprel = table_open(heapid, lockmode);
-
-		/*
-		 * Switch to the table owner's userid, so that any index functions are
-		 * run as that user.  Also lock down security-restricted operations
-		 * and arrange to make GUC variable changes local to this command.
-		 */
-		GetUserIdAndSecContext(&save_userid, &save_sec_context);
-		SetUserIdAndSecContext(heaprel->rd_rel->relowner,
-							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
-		save_nestlevel = NewGUCNestLevel();
-		RestrictSearchPath();
-	}
-	else
-	{
-		heaprel = NULL;
-		/* Set these just to suppress "uninitialized variable" warnings */
-		save_userid = InvalidOid;
-		save_sec_context = -1;
-		save_nestlevel = -1;
-	}
+	BTCallbackState *args = (BTCallbackState *) state;
+	bool		heapkeyspace,
+				allequalimage;
 
-	/*
-	 * Open the target index relations separately (like relation_openrv(), but
-	 * with heap relation locked first to prevent deadlocking).  In hot
-	 * standby mode this will raise an error when parentcheck is true.
-	 *
-	 * There is no need for the usual indcheckxmin usability horizon test
-	 * here, even in the heapallindexed case, because index undergoing
-	 * verification only needs to have entries for a new transaction snapshot.
-	 * (If this is a parentcheck verification, there is no question about
-	 * committed or recently dead heap tuples lacking index entries due to
-	 * concurrent activity.)
-	 */
-	indrel = index_open(indrelid, lockmode);
-
-	/*
-	 * Since we did the IndexGetRelation call above without any lock, it's
-	 * barely possible that a race against an index drop/recreation could have
-	 * netted us the wrong table.
-	 */
-	if (heaprel == NULL || heapid != IndexGetRelation(indrelid, false))
+	if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
 		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 errmsg("could not open parent table of index \"%s\"",
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" lacks a main relation fork",
 						RelationGetRelationName(indrel))));
 
-	/* Relation suitable for checking as B-Tree? */
-	btree_index_checkable(indrel);
-
-	if (btree_index_mainfork_expected(indrel))
+	/* Extract metadata from metapage, and sanitize it in passing */
+	_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
+	if (allequalimage && !heapkeyspace)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
+						RelationGetRelationName(indrel))));
+	if (allequalimage && !_bt_allequalimage(indrel, false))
 	{
-		bool		heapkeyspace,
-					allequalimage;
+		bool		has_interval_ops = false;
 
-		if (!smgrexists(RelationGetSmgr(indrel), MAIN_FORKNUM))
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" lacks a main relation fork",
-							RelationGetRelationName(indrel))));
-
-		/* Extract metadata from metapage, and sanitize it in passing */
-		_bt_metaversion(indrel, &heapkeyspace, &allequalimage);
-		if (allequalimage && !heapkeyspace)
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage has equalimage field set on unsupported nbtree version",
-							RelationGetRelationName(indrel))));
-		if (allequalimage && !_bt_allequalimage(indrel, false))
-		{
-			bool		has_interval_ops = false;
-
-			for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
-				if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
-					has_interval_ops = true;
-			ereport(ERROR,
-					(errcode(ERRCODE_INDEX_CORRUPTED),
-					 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
-							RelationGetRelationName(indrel)),
-					 has_interval_ops
-					 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
-					 : 0));
-		}
-
-		/* Check index, possibly against table it is an index on */
-		bt_check_every_level(indrel, heaprel, heapkeyspace, parentcheck,
-							 heapallindexed, rootdescend, checkunique);
+		for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(indrel); i++)
+			if (indrel->rd_opfamily[i] == INTERVAL_BTREE_FAM_OID)
+			{
+				has_interval_ops = true;
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" metapage incorrectly indicates that deduplication is safe",
+								RelationGetRelationName(indrel)),
+						 has_interval_ops
+						 ? errhint("This is known of \"interval\" indexes last built on a version predating 2023-11.")
+						 : 0));
+			}
 	}
 
-	/* Roll back any GUC changes executed by index functions */
-	AtEOXact_GUC(false, save_nestlevel);
-
-	/* Restore userid and security context */
-	SetUserIdAndSecContext(save_userid, save_sec_context);
-
-	/*
-	 * Release locks early. That's ok here because nothing in the called
-	 * routines will trigger shared cache invalidations to be sent, so we can
-	 * relax the usual pattern of only releasing locks after commit.
-	 */
-	index_close(indrel, lockmode);
-	if (heaprel)
-		table_close(heaprel, lockmode);
-}
-
-/*
- * Basic checks about the suitability of a relation for checking as a B-Tree
- * index.
- *
- * NB: Intentionally not checking permissions, the function is normally not
- * callable by non-superusers. If granted, it's useful to be able to check a
- * whole cluster.
- */
-static inline void
-btree_index_checkable(Relation rel)
-{
-	if (rel->rd_rel->relkind != RELKIND_INDEX ||
-		rel->rd_rel->relam != BTREE_AM_OID)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("only B-Tree indexes are supported as targets for verification"),
-				 errdetail("Relation \"%s\" is not a B-Tree index.",
-						   RelationGetRelationName(rel))));
-
-	if (RELATION_IS_OTHER_TEMP(rel))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot access temporary tables of other sessions"),
-				 errdetail("Index \"%s\" is associated with temporary relation.",
-						   RelationGetRelationName(rel))));
-
-	if (!rel->rd_index->indisvalid)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot check index \"%s\"",
-						RelationGetRelationName(rel)),
-				 errdetail("Index is not valid.")));
-}
-
-/*
- * Check if B-Tree index relation should have a file for its main relation
- * fork.  Verification uses this to skip unlogged indexes when in hot standby
- * mode, where there is simply nothing to verify.  We behave as if the
- * relation is empty.
- *
- * NB: Caller should call btree_index_checkable() before calling here.
- */
-static inline bool
-btree_index_mainfork_expected(Relation rel)
-{
-	if (rel->rd_rel->relpersistence != RELPERSISTENCE_UNLOGGED ||
-		!RecoveryInProgress())
-		return true;
-
-	ereport(DEBUG1,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("cannot verify unlogged index \"%s\" during recovery, skipping",
-					RelationGetRelationName(rel))));
-
-	return false;
+	/* Check index, possibly against table it is an index on */
+	bt_check_every_level(indrel, heaprel, heapkeyspace, readonly,
+						 args->heapallindexed, args->rootdescend, args->checkunique);
 }
 
 /*
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 1279b69422a..b66affbea56 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -194,6 +194,7 @@ BOOLEAN
 BOX
 BTArrayKeyInfo
 BTBuildState
+BTCallbackState
 BTCycleId
 BTDedupInterval
 BTDedupState
-- 
2.49.0

From 9f85cac7e03aa9e24fad52399949c0dc4858dda8 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Fri, 28 Mar 2025 16:08:05 +0100
Subject: [PATCH v20250328 3/6] amcheck: Add gin_index_check() to verify GIN
 index
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The new functions validates two kinds of invariants on a GIN index:

- parent-child consistency: Paths in a GIN graph have to contain
  consistent keys: tuples on parent pages consistently include tuples
  from children pages. That is, parent tuples must not require any
  adjustments.

- balanced-tree / graph: Each internal page has at least one downlink,
  and can reference either only leaf pages or only internal pages.

The GIN verification is based on work by Grigory Kryachko, reworked by
Heikki Linnakangas and with various improvements by Andrey Borodin.
Investigation and fixes for a couple bugs by Kirill Reshke.

Author: Grigory Kryachko <GSKryachko@gmail.com>
Author: Heikki Linnakangas <hlinnaka@iki.fi>
Author: Andrey Borodin <amborodin@acm.org>
Reviewed-By: José Villanova <jose.arthur@gmail.com>
Reviewed-By: Aleksander Alekseev <aleksander@timescale.com>
Reviewed-By: Nikolay Samokhvalov <samokhvalov@gmail.com>
Reviewed-By: Andres Freund <andres@anarazel.de>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Reviewed-By: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-By: Mark Dilger <mark.dilger@enterprisedb.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/45AC9B0A-2B45-40EE-B08F-BDCF5739D1E1%40yandex-team.ru
---
 contrib/amcheck/Makefile               |   6 +-
 contrib/amcheck/amcheck--1.4--1.5.sql  |  14 +
 contrib/amcheck/amcheck.control        |   2 +-
 contrib/amcheck/expected/check_gin.out |  64 ++
 contrib/amcheck/meson.build            |   3 +
 contrib/amcheck/sql/check_gin.sql      |  40 ++
 contrib/amcheck/verify_gin.c           | 798 +++++++++++++++++++++++++
 doc/src/sgml/amcheck.sgml              |  20 +
 src/tools/pgindent/typedefs.list       |   2 +
 9 files changed, 946 insertions(+), 3 deletions(-)
 create mode 100644 contrib/amcheck/amcheck--1.4--1.5.sql
 create mode 100644 contrib/amcheck/expected/check_gin.out
 create mode 100644 contrib/amcheck/sql/check_gin.sql
 create mode 100644 contrib/amcheck/verify_gin.c

diff --git a/contrib/amcheck/Makefile b/contrib/amcheck/Makefile
index c3d70f3369c..1b7a63cbaa4 100644
--- a/contrib/amcheck/Makefile
+++ b/contrib/amcheck/Makefile
@@ -4,14 +4,16 @@ MODULE_big	= amcheck
 OBJS = \
 	$(WIN32RES) \
 	verify_common.o \
+	verify_gin.o \
 	verify_heapam.o \
 	verify_nbtree.o
 
 EXTENSION = amcheck
-DATA = amcheck--1.3--1.4.sql amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql
+DATA = amcheck--1.2--1.3.sql amcheck--1.1--1.2.sql amcheck--1.0--1.1.sql amcheck--1.0.sql \
+		amcheck--1.3--1.4.sql amcheck--1.4--1.5.sql
 PGFILEDESC = "amcheck - function for verifying relation integrity"
 
-REGRESS = check check_btree check_heap
+REGRESS = check check_btree check_gin check_heap
 
 EXTRA_INSTALL = contrib/pg_walinspect
 TAP_TESTS = 1
diff --git a/contrib/amcheck/amcheck--1.4--1.5.sql b/contrib/amcheck/amcheck--1.4--1.5.sql
new file mode 100644
index 00000000000..445c48ccb7d
--- /dev/null
+++ b/contrib/amcheck/amcheck--1.4--1.5.sql
@@ -0,0 +1,14 @@
+/* contrib/amcheck/amcheck--1.4--1.5.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "ALTER EXTENSION amcheck UPDATE TO '1.5'" to load this file. \quit
+
+
+-- gin_index_check()
+--
+CREATE FUNCTION gin_index_check(index regclass)
+RETURNS VOID
+AS 'MODULE_PATHNAME', 'gin_index_check'
+LANGUAGE C STRICT;
+
+REVOKE ALL ON FUNCTION gin_index_check(regclass) FROM PUBLIC;
diff --git a/contrib/amcheck/amcheck.control b/contrib/amcheck/amcheck.control
index e67ace01c99..c8ba6d7c9bc 100644
--- a/contrib/amcheck/amcheck.control
+++ b/contrib/amcheck/amcheck.control
@@ -1,5 +1,5 @@
 # amcheck extension
 comment = 'functions for verifying relation integrity'
-default_version = '1.4'
+default_version = '1.5'
 module_pathname = '$libdir/amcheck'
 relocatable = true
diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
new file mode 100644
index 00000000000..bbcde80e627
--- /dev/null
+++ b/contrib/amcheck/expected/check_gin.out
@@ -0,0 +1,64 @@
+-- Test of index bulk load
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test index inserts
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+SELECT gin_index_check('gin_check_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check;
+-- Test GIN over text array
+SELECT setseed(1);
+ setseed 
+---------
+ 
+(1 row)
+
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index 67a4ac8518d..b33e8c9b062 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -2,6 +2,7 @@
 
 amcheck_sources = files(
   'verify_common.c',
+  'verify_gin.c',
   'verify_heapam.c',
   'verify_nbtree.c',
 )
@@ -25,6 +26,7 @@ install_data(
   'amcheck--1.1--1.2.sql',
   'amcheck--1.2--1.3.sql',
   'amcheck--1.3--1.4.sql',
+  'amcheck--1.4--1.5.sql',
   kwargs: contrib_data_args,
 )
 
@@ -36,6 +38,7 @@ tests += {
     'sql': [
       'check',
       'check_btree',
+      'check_gin',
       'check_heap',
     ],
   },
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
new file mode 100644
index 00000000000..bbd9b9f8281
--- /dev/null
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -0,0 +1,40 @@
+-- Test of index bulk load
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+-- posting trees (frequently used entries)
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves (sparse entries)
+INSERT INTO gin_check select array_agg(255 + round(random()*100)) from generate_series(1, 100) as i group by i % 100;
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test index inserts
+SELECT setseed(1);
+CREATE TABLE "gin_check"("Column1" int[]);
+CREATE INDEX gin_check_idx on "gin_check" USING GIN("Column1");
+ALTER INDEX gin_check_idx SET (fastupdate = false);
+-- posting trees
+INSERT INTO gin_check select array_agg(round(random()*255) ) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check select array_agg(100 + round(random()*255)) from generate_series(1, 100) as i group by i % 100;
+
+SELECT gin_index_check('gin_check_idx');
+
+-- cleanup
+DROP TABLE gin_check;
+
+-- Test GIN over text array
+SELECT setseed(1);
+CREATE TABLE "gin_check_text_array"("Column1" text[]);
+-- posting trees
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300)::text)::text) from generate_series(1, 100000) as i group by i % 10000;
+-- posting leaves
+INSERT INTO gin_check_text_array select array_agg(md5(round(random()*300 + 300)::text)::text) from generate_series(1, 10000) as i group by i % 100;
+CREATE INDEX gin_check_text_array_idx on "gin_check_text_array" USING GIN("Column1");
+SELECT gin_index_check('gin_check_text_array_idx');
+
+-- cleanup
+DROP TABLE gin_check_text_array;
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
new file mode 100644
index 00000000000..670f53637d4
--- /dev/null
+++ b/contrib/amcheck/verify_gin.c
@@ -0,0 +1,798 @@
+/*-------------------------------------------------------------------------
+ *
+ * verify_gin.c
+ *		Verifies the integrity of GIN indexes based on invariants.
+ *
+ *
+ * GIN index verification checks a number of invariants:
+ *
+ * - consistency: Paths in GIN graph have to contain consistent keys: tuples
+ *   on parent pages consistently include tuples from children pages.
+ *
+ * - graph invariants: Each internal page must have at least one downlink, and
+ *   can reference either only leaf pages or only internal pages.
+ *
+ *
+ * Copyright (c) 2016-2025, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  contrib/amcheck/verify_gin.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/gin_private.h"
+#include "access/nbtree.h"
+#include "catalog/pg_am.h"
+#include "utils/memutils.h"
+#include "utils/rel.h"
+#include "verify_common.h"
+#include "string.h"
+
+/*
+ * GinScanItem represents one item of depth-first scan of the index.
+ */
+typedef struct GinScanItem
+{
+	int			depth;
+	IndexTuple	parenttup;
+	BlockNumber parentblk;
+	XLogRecPtr	parentlsn;
+	BlockNumber blkno;
+	struct GinScanItem *next;
+} GinScanItem;
+
+/*
+ * GinPostingTreeScanItem represents one item of a depth-first posting tree scan.
+ */
+typedef struct GinPostingTreeScanItem
+{
+	int			depth;
+	ItemPointerData parentkey;
+	BlockNumber parentblk;
+	BlockNumber blkno;
+	struct GinPostingTreeScanItem *next;
+} GinPostingTreeScanItem;
+
+
+PG_FUNCTION_INFO_V1(gin_index_check);
+
+static void gin_check_parent_keys_consistency(Relation rel,
+											  Relation heaprel,
+											  void *callback_state, bool readonly);
+static void check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo);
+static IndexTuple gin_refind_parent(Relation rel,
+									BlockNumber parentblkno,
+									BlockNumber childblkno,
+									BufferAccessStrategy strategy);
+static ItemId PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+								   OffsetNumber offset);
+
+/*
+ * gin_index_check(index regclass)
+ *
+ * Verify integrity of GIN index.
+ *
+ * Acquires AccessShareLock on heap & index relations.
+ */
+Datum
+gin_index_check(PG_FUNCTION_ARGS)
+{
+	Oid			indrelid = PG_GETARG_OID(0);
+
+	amcheck_lock_relation_and_check(indrelid,
+									GIN_AM_OID,
+									gin_check_parent_keys_consistency,
+									AccessShareLock,
+									NULL);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Read item pointers from leaf entry tuple.
+ *
+ * Returns a palloc'd array of ItemPointers. The number of items is returned
+ * in *nitems.
+ */
+static ItemPointer
+ginReadTupleWithoutState(IndexTuple itup, int *nitems)
+{
+	Pointer		ptr = GinGetPosting(itup);
+	int			nipd = GinGetNPosting(itup);
+	ItemPointer ipd;
+	int			ndecoded;
+
+	if (GinItupIsCompressed(itup))
+	{
+		if (nipd > 0)
+		{
+			ipd = ginPostingListDecode((GinPostingList *) ptr, &ndecoded);
+			if (nipd != ndecoded)
+				elog(ERROR, "number of items mismatch in GIN entry tuple, %d in tuple header, %d decoded",
+					 nipd, ndecoded);
+		}
+		else
+			ipd = palloc(0);
+	}
+	else
+	{
+		ipd = (ItemPointer) palloc(sizeof(ItemPointerData) * nipd);
+		memcpy(ipd, ptr, sizeof(ItemPointerData) * nipd);
+	}
+	*nitems = nipd;
+	return ipd;
+}
+
+/*
+ * Scans through a posting tree (given by the root), and verifies that the keys
+ * on a child keys are consistent with the parent.
+ *
+ * Allocates a separate memory context and scans through posting tree graph.
+ */
+static void
+gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting_tree_root)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinPostingTreeScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "posting tree check context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinPostingTreeScanItem *) palloc0(sizeof(GinPostingTreeScanItem));
+	stack->depth = 0;
+	ItemPointerSetInvalid(&stack->parentkey);
+	stack->parentblk = InvalidBlockNumber;
+	stack->blkno = posting_tree_root;
+
+	elog(DEBUG3, "processing posting tree at blk %u", posting_tree_root);
+
+	while (stack)
+	{
+		GinPostingTreeScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff;
+		BlockNumber rightlink;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+
+		Assert(GinPageIsData(page));
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			ItemPointerData minItem;
+			int			nlist;
+			ItemPointerData *list;
+			char		tidrange_buf[MAXPGPATH];
+
+			ItemPointerSetMin(&minItem);
+
+			elog(DEBUG1, "page blk: %u, type leaf", stack->blkno);
+
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+			list = GinDataLeafPageGetItems(page, &nlist, minItem);
+
+			if (nlist > 0)
+				snprintf(tidrange_buf, sizeof(tidrange_buf),
+						 "%d tids (%u, %u) - (%u, %u)",
+						 nlist,
+						 ItemPointerGetBlockNumberNoCheck(&list[0]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[0]),
+						 ItemPointerGetBlockNumberNoCheck(&list[nlist - 1]),
+						 ItemPointerGetOffsetNumberNoCheck(&list[nlist - 1]));
+			else
+				snprintf(tidrange_buf, sizeof(tidrange_buf), "0 tids");
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: parent %u highkey (%u, %u), %s",
+					 stack->blkno,
+					 stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey),
+					 tidrange_buf);
+			else
+				elog(DEBUG3, "blk %u: root leaf, %s",
+					 stack->blkno,
+					 tidrange_buf);
+
+			if (stack->parentblk != InvalidBlockNumber &&
+				ItemPointerGetOffsetNumberNoCheck(&stack->parentkey) != InvalidOffsetNumber &&
+				nlist > 0 && ItemPointerCompare(&stack->parentkey, &list[nlist - 1]) < 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": tid exceeds parent's high key in postingTree leaf on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+		else
+		{
+			LocationIndex pd_lower;
+			ItemPointerData bound;
+			int			lowersize;
+
+			/*
+			 * Check that tuples in each page are properly ordered and
+			 * consistent with parent high key
+			 */
+			maxoff = GinPageGetOpaque(page)->maxoff;
+			rightlink = GinPageGetOpaque(page)->rightlink;
+
+			elog(DEBUG1, "page blk: %u, type data, maxoff %d", stack->blkno, maxoff);
+
+			if (stack->parentblk != InvalidBlockNumber)
+				elog(DEBUG3, "blk %u: internal posting tree page with %u items, parent %u highkey (%u, %u)",
+					 stack->blkno, maxoff, stack->parentblk,
+					 ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+					 ItemPointerGetOffsetNumberNoCheck(&stack->parentkey));
+			else
+				elog(DEBUG3, "blk %u: root internal posting tree page with %u items",
+					 stack->blkno, maxoff);
+
+			/*
+			 * A GIN posting tree internal page stores PostingItems in the
+			 * 'lower' part of the page. The 'upper' part is unused. The
+			 * number of elements is stored in the opaque area (maxoff). Make
+			 * sure the size of the 'lower' part agrees with 'maxoff'
+			 *
+			 * We didn't set pd_lower until PostgreSQL version 9.4, so if this
+			 * check fails, it could also be because the index was
+			 * binary-upgraded from an earlier version. That was a long time
+			 * ago, though, so let's warn if it doesn't match.
+			 */
+			pd_lower = ((PageHeader) page)->pd_lower;
+			lowersize = pd_lower - MAXALIGN(SizeOfPageHeaderData);
+			if ((lowersize - MAXALIGN(sizeof(ItemPointerData))) / sizeof(PostingItem) != maxoff)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has unexpected pd_lower %u in posting tree block %u with maxoff %u)",
+								RelationGetRelationName(rel), pd_lower, stack->blkno, maxoff)));
+
+			/*
+			 * Before the PostingItems, there's one ItemPointerData in the
+			 * 'lower' part that stores the page's high key.
+			 */
+			bound = *GinDataPageGetRightBound(page);
+
+			/*
+			 * Gin page right bound has a sane value only when not a highkey on
+			 * the rightmost page (at a given level). For the rightmost page does
+			 * not store the highkey explicitly, and the value is infinity.
+			 */
+			if (ItemPointerIsValid(&stack->parentkey) &&
+				rightlink != InvalidBlockNumber &&
+				!ItemPointerEquals(&stack->parentkey, &bound))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": posting tree page's high key (%u, %u) doesn't match the downlink on block %u (parent blk %u, key (%u, %u))",
+								RelationGetRelationName(rel),
+								ItemPointerGetBlockNumberNoCheck(&bound),
+								ItemPointerGetOffsetNumberNoCheck(&bound),
+								stack->blkno, stack->parentblk,
+								ItemPointerGetBlockNumberNoCheck(&stack->parentkey),
+								ItemPointerGetOffsetNumberNoCheck(&stack->parentkey))));
+
+			for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+			{
+				GinPostingTreeScanItem *ptr;
+				PostingItem *posting_item = GinDataPageGetPostingItem(page, i);
+
+				/* ItemPointerGetOffsetNumber expects a valid pointer */
+				if (!(i == maxoff &&
+					  rightlink == InvalidBlockNumber))
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 ItemPointerGetBlockNumber(&posting_item->key),
+						 ItemPointerGetOffsetNumber(&posting_item->key),
+						 BlockIdGetBlockNumber(&posting_item->child_blkno));
+				else
+					elog(DEBUG3, "key (%u, %u) -> %u",
+						 0, 0, BlockIdGetBlockNumber(&posting_item->child_blkno));
+
+				if (i == maxoff && rightlink == InvalidBlockNumber)
+				{
+					/*
+					 * The rightmost item in the tree level has (0, 0) as the
+					 * key
+					 */
+					if (ItemPointerGetBlockNumberNoCheck(&posting_item->key) != 0 ||
+						ItemPointerGetOffsetNumberNoCheck(&posting_item->key) != 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": rightmost posting tree page (blk %u) has unexpected last key (%u, %u)",
+										RelationGetRelationName(rel),
+										stack->blkno,
+										ItemPointerGetBlockNumberNoCheck(&posting_item->key),
+										ItemPointerGetOffsetNumberNoCheck(&posting_item->key))));
+				}
+				else if (i != FirstOffsetNumber)
+				{
+					PostingItem *previous_posting_item = GinDataPageGetPostingItem(page, i - 1);
+
+					if (ItemPointerCompare(&posting_item->key, &previous_posting_item->key) < 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\" has wrong tuple order in posting tree, block %u, offset %u",
+										RelationGetRelationName(rel), stack->blkno, i)));
+				}
+
+				/*
+				 * Check if this tuple is consistent with the downlink in the
+				 * parent.
+				 */
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\": posting item exceeds parent's high key in postingTree internal page on block %u offset %u",
+									RelationGetRelationName(rel),
+									stack->blkno, i)));
+
+				/* This is an internal page, recurse into the child. */
+				ptr = (GinPostingTreeScanItem *) palloc(sizeof(GinPostingTreeScanItem));
+				ptr->depth = stack->depth + 1;
+
+				/*
+				 * Set rightmost parent key to invalid iterm pointer. Its
+				 * value is 'Infinity' and not explicitly stored.
+				 */
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
+					ptr->parentkey = posting_item->key;
+
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Main entry point for GIN checks.
+ *
+ * Allocates memory context and scans through the whole GIN graph.
+ */
+static void
+gin_check_parent_keys_consistency(Relation rel,
+								  Relation heaprel,
+								  void *callback_state,
+								  bool readonly)
+{
+	BufferAccessStrategy strategy = GetAccessStrategy(BAS_BULKREAD);
+	GinScanItem *stack;
+	MemoryContext mctx;
+	MemoryContext oldcontext;
+	GinState	state;
+	int			leafdepth;
+
+	mctx = AllocSetContextCreate(CurrentMemoryContext,
+								 "amcheck consistency check context",
+								 ALLOCSET_DEFAULT_SIZES);
+	oldcontext = MemoryContextSwitchTo(mctx);
+	initGinState(&state, rel);
+
+	/*
+	 * We don't know the height of the tree yet, but as soon as we encounter a
+	 * leaf page, we will set 'leafdepth' to its depth.
+	 */
+	leafdepth = -1;
+
+	/* Start the scan at the root page */
+	stack = (GinScanItem *) palloc0(sizeof(GinScanItem));
+	stack->depth = 0;
+	stack->parenttup = NULL;
+	stack->parentblk = InvalidBlockNumber;
+	stack->parentlsn = InvalidXLogRecPtr;
+	stack->blkno = GIN_ROOT_BLKNO;
+
+	while (stack)
+	{
+		GinScanItem *stack_next;
+		Buffer		buffer;
+		Page		page;
+		OffsetNumber i,
+					maxoff,
+					prev_attnum;
+		XLogRecPtr	lsn;
+		IndexTuple	prev_tuple;
+		BlockNumber rightlink;
+
+		CHECK_FOR_INTERRUPTS();
+
+		buffer = ReadBufferExtended(rel, MAIN_FORKNUM, stack->blkno,
+									RBM_NORMAL, strategy);
+		LockBuffer(buffer, GIN_SHARE);
+		page = (Page) BufferGetPage(buffer);
+		lsn = BufferGetLSNAtomic(buffer);
+		maxoff = PageGetMaxOffsetNumber(page);
+		rightlink = GinPageGetOpaque(page)->rightlink;
+
+		/* Do basic sanity checks on the page headers */
+		check_index_page(rel, buffer, stack->blkno);
+
+		elog(DEBUG3, "processing entry tree page at blk %u, maxoff: %u", stack->blkno, maxoff);
+
+		/*
+		 * It's possible that the page was split since we looked at the
+		 * parent, so that we didn't missed the downlink of the right sibling
+		 * when we scanned the parent.  If so, add the right sibling to the
+		 * stack now.
+		 */
+		if (stack->parenttup != NULL)
+		{
+			GinNullCategory parent_key_category;
+			Datum		parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
+												   page, maxoff);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory page_max_key_category;
+			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
+
+			if (rightlink != InvalidBlockNumber &&
+				ginCompareEntries(&state, attnum, page_max_key,
+								  page_max_key_category, parent_key,
+								  parent_key_category) > 0)
+			{
+				/* split page detected, install right link to the stack */
+				GinScanItem *ptr;
+
+				elog(DEBUG3, "split detected for blk: %u, parent blk: %u", stack->blkno, stack->parentblk);
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth;
+				ptr->parenttup = CopyIndexTuple(stack->parenttup);
+				ptr->parentblk = stack->parentblk;
+				ptr->parentlsn = stack->parentlsn;
+				ptr->blkno = rightlink;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+		}
+
+		/* Check that the tree has the same height in all branches */
+		if (GinPageIsLeaf(page))
+		{
+			if (leafdepth == -1)
+				leafdepth = stack->depth;
+			else if (stack->depth != leafdepth)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\": internal pages traversal encountered leaf page unexpectedly on block %u",
+								RelationGetRelationName(rel), stack->blkno)));
+		}
+
+		/*
+		 * Check that tuples in each page are properly ordered and consistent
+		 * with parent high key
+		 */
+		prev_tuple = NULL;
+		prev_attnum = InvalidAttrNumber;
+		for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
+		{
+			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
+			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
+			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			GinNullCategory prev_key_category;
+			Datum		prev_key;
+			GinNullCategory current_key_category;
+			Datum		current_key;
+
+			if (MAXALIGN(ItemIdGetLength(iid)) != MAXALIGN(IndexTupleSize(idxtuple)))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+						 errmsg("index \"%s\" has inconsistent tuple sizes, block %u, offset %u",
+								RelationGetRelationName(rel), stack->blkno, i)));
+
+			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
+
+			/*
+			 * First block is metadata, skip order check. Also, never check
+			 * for high key on rightmost page, as this key is not really
+			 * stored explicitly.
+			 *
+			 * Also make sure to not compare entries for different attnums, which
+			 * may be stored on the same page.
+			 */
+			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
+				!(i == maxoff && rightlink == InvalidBlockNumber))
+			{
+				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
+				if (ginCompareEntries(&state, attnum, prev_key,
+									  prev_key_category, current_key,
+									  current_key_category) >= 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_INDEX_CORRUPTED),
+							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
+									RelationGetRelationName(rel), stack->blkno, i, rightlink)));
+			}
+
+			/*
+			 * Check if this tuple is consistent with the downlink in the
+			 * parent.
+			 */
+			if (stack->parenttup &&
+				i == maxoff)
+			{
+				GinNullCategory parent_key_category;
+				Datum		parent_key = gintuple_get_key(&state,
+														  stack->parenttup,
+														  &parent_key_category);
+
+				if (ginCompareEntries(&state, attnum, current_key,
+									  current_key_category, parent_key,
+									  parent_key_category) > 0)
+				{
+					/*
+					 * There was a discrepancy between parent and child
+					 * tuples. We need to verify it is not a result of
+					 * concurrent call of gistplacetopage(). So, lock parent
+					 * and try to find downlink for current page. It may be
+					 * missing due to concurrent page split, this is OK.
+					 */
+					pfree(stack->parenttup);
+					stack->parenttup = gin_refind_parent(rel, stack->parentblk,
+														 stack->blkno, strategy);
+
+					/* We found it - make a final check before failing */
+					if (!stack->parenttup)
+						elog(NOTICE, "Unable to find parent tuple for block %u on block %u due to concurrent split",
+							 stack->blkno, stack->parentblk);
+					else
+					{
+						parent_key = gintuple_get_key(&state,
+													  stack->parenttup,
+													  &parent_key_category);
+
+						/*
+						 * Check if it is properly adjusted. If succeed,
+						 * procced to the next key.
+						 */
+						if (ginCompareEntries(&state, attnum, current_key,
+											  current_key_category, parent_key,
+											  parent_key_category) > 0)
+							ereport(ERROR,
+									(errcode(ERRCODE_INDEX_CORRUPTED),
+									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
+											RelationGetRelationName(rel), stack->blkno, i)));
+					}
+				}
+			}
+
+			/* If this is an internal page, recurse into the child */
+			if (!GinPageIsLeaf(page))
+			{
+				GinScanItem *ptr;
+
+				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
+				ptr->depth = stack->depth + 1;
+				/* last tuple in layer has no high key */
+				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
+					ptr->parenttup = CopyIndexTuple(idxtuple);
+				else
+					ptr->parenttup = NULL;
+				ptr->parentblk = stack->blkno;
+				ptr->blkno = GinGetDownlink(idxtuple);
+				ptr->parentlsn = lsn;
+				ptr->next = stack->next;
+				stack->next = ptr;
+			}
+			/* If this item is a pointer to a posting tree, recurse into it */
+			else if (GinIsPostingTree(idxtuple))
+			{
+				BlockNumber rootPostingTree = GinGetPostingTree(idxtuple);
+
+				gin_check_posting_tree_parent_keys_consistency(rel, rootPostingTree);
+			}
+			else
+			{
+				ItemPointer ipd;
+				int			nipd;
+
+				ipd = ginReadTupleWithoutState(idxtuple, &nipd);
+
+				for (int j = 0; j < nipd; j++)
+				{
+					if (!OffsetNumberIsValid(ItemPointerGetOffsetNumber(&ipd[j])))
+						ereport(ERROR,
+								(errcode(ERRCODE_INDEX_CORRUPTED),
+								 errmsg("index \"%s\": posting list contains invalid heap pointer on block %u",
+										RelationGetRelationName(rel), stack->blkno)));
+				}
+				pfree(ipd);
+			}
+
+			prev_tuple = CopyIndexTuple(idxtuple);
+			prev_attnum = attnum;
+		}
+
+		LockBuffer(buffer, GIN_UNLOCK);
+		ReleaseBuffer(buffer);
+
+		/* Step to next item in the queue */
+		stack_next = stack->next;
+		if (stack->parenttup)
+			pfree(stack->parenttup);
+		pfree(stack);
+		stack = stack_next;
+	}
+
+	MemoryContextSwitchTo(oldcontext);
+	MemoryContextDelete(mctx);
+}
+
+/*
+ * Verify that a freshly-read page looks sane.
+ */
+static void
+check_index_page(Relation rel, Buffer buffer, BlockNumber blockNo)
+{
+	Page		page = BufferGetPage(buffer);
+
+	/*
+	 * ReadBuffer verifies that every newly-read page passes
+	 * PageHeaderIsValid, which means it either contains a reasonably sane
+	 * page header or is all-zero.  We have to defend against the all-zero
+	 * case, however.
+	 */
+	if (PageIsNew(page))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains unexpected zero page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	/*
+	 * Additionally check that the special area looks sane.
+	 */
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" contains corrupted page at block %u",
+						RelationGetRelationName(rel),
+						BufferGetBlockNumber(buffer)),
+				 errhint("Please REINDEX it.")));
+
+	if (GinPageIsDeleted(page))
+	{
+		if (!GinPageIsLeaf(page))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted internal page %d",
+							RelationGetRelationName(rel), blockNo)));
+		if (PageGetMaxOffsetNumber(page) > InvalidOffsetNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_INDEX_CORRUPTED),
+					 errmsg("index \"%s\" has deleted page %d with tuples",
+							RelationGetRelationName(rel), blockNo)));
+	}
+	else if (PageGetMaxOffsetNumber(page) > MaxIndexTuplesPerPage)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("index \"%s\" has page %d with exceeding count of tuples",
+						RelationGetRelationName(rel), blockNo)));
+}
+
+/*
+ * Try to re-find downlink pointing to 'blkno', in 'parentblkno'.
+ *
+ * If found, returns a palloc'd copy of the downlink tuple. Otherwise,
+ * returns NULL.
+ */
+static IndexTuple
+gin_refind_parent(Relation rel, BlockNumber parentblkno,
+				  BlockNumber childblkno, BufferAccessStrategy strategy)
+{
+	Buffer		parentbuf;
+	Page		parentpage;
+	OffsetNumber o,
+				parent_maxoff;
+	IndexTuple	result = NULL;
+
+	parentbuf = ReadBufferExtended(rel, MAIN_FORKNUM, parentblkno, RBM_NORMAL,
+								   strategy);
+
+	LockBuffer(parentbuf, GIN_SHARE);
+	parentpage = BufferGetPage(parentbuf);
+
+	if (GinPageIsLeaf(parentpage))
+	{
+		UnlockReleaseBuffer(parentbuf);
+		return result;
+	}
+
+	parent_maxoff = PageGetMaxOffsetNumber(parentpage);
+	for (o = FirstOffsetNumber; o <= parent_maxoff; o = OffsetNumberNext(o))
+	{
+		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
+		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
+
+		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		{
+			/* Found it! Make copy and return it */
+			result = CopyIndexTuple(itup);
+			break;
+		}
+	}
+
+	UnlockReleaseBuffer(parentbuf);
+
+	return result;
+}
+
+static ItemId
+PageGetItemIdCareful(Relation rel, BlockNumber block, Page page,
+					 OffsetNumber offset)
+{
+	ItemId		itemid = PageGetItemId(page, offset);
+
+	if (ItemIdGetOffset(itemid) + ItemIdGetLength(itemid) >
+		BLCKSZ - MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("line pointer points past end of tuple space in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	/*
+	 * Verify that line pointer isn't LP_REDIRECT or LP_UNUSED or LP_DEAD,
+	 * since GIN never uses all three.  Verify that line pointer has storage,
+	 * too.
+	 */
+	if (ItemIdIsRedirected(itemid) || !ItemIdIsUsed(itemid) ||
+		ItemIdIsDead(itemid) || ItemIdGetLength(itemid) == 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg("invalid line pointer storage in index \"%s\"",
+						RelationGetRelationName(rel)),
+				 errdetail_internal("Index tid=(%u,%u) lp_off=%u, lp_len=%u lp_flags=%u.",
+									block, offset, ItemIdGetOffset(itemid),
+									ItemIdGetLength(itemid),
+									ItemIdGetFlags(itemid))));
+
+	return itemid;
+}
diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml
index a12aa3abf01..98f836e15e7 100644
--- a/doc/src/sgml/amcheck.sgml
+++ b/doc/src/sgml/amcheck.sgml
@@ -188,6 +188,26 @@ ORDER BY c.relpages DESC LIMIT 10;
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_index_check(index regclass) returns void</function>
+     <indexterm>
+      <primary>gin_index_check</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_index_check</function> tests that its target GIN index
+      has consistent parent-child tuples relations (no parent tuples
+      require tuple adjustement) and page graph respects balanced-tree
+      invariants (internal pages reference only leaf page or only internal
+      pages).
+     </para>
+    </listitem>
+   </varlistentry>
+
   </variablelist>
   <tip>
    <para>
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index b66affbea56..b66cecd8799 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1053,8 +1053,10 @@ GinPageOpaque
 GinPageOpaqueData
 GinPlaceToPageRC
 GinPostingList
+GinPostingTreeScanItem
 GinQualCounts
 GinScanEntry
+GinScanItem
 GinScanKey
 GinScanOpaque
 GinScanOpaqueData
-- 
2.49.0

From d11a04e9712e7f278923c2ad2474f9d251174263 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Fri, 28 Mar 2025 16:53:31 +0100
Subject: [PATCH v20250328 4/6] amcheck: Add a test with GIN index on JSONB
 data

Extend the existing test of GIN checks to also include an index on JSONB
data, using the jsonb_path_ops opclass. This is a common enough usage of
GIN that it makes sense to have better test coverage for it.

Author: Mark Dilger <mark.dilger@enterprisedb.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Reviewed-By: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://postgr.es/m/BC221A56-977C-418E-A1B8-9EFC881D80C5%40enterprisedb.com
---
 contrib/amcheck/expected/check_gin.out | 14 ++++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 12 ++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index bbcde80e627..93147de0ef1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -62,3 +62,17 @@ SELECT gin_index_check('gin_check_text_array_idx');
 
 -- cleanup
 DROP TABLE gin_check_text_array;
+-- Test GIN over jsonb
+CREATE TABLE "gin_check_jsonb"("j" jsonb);
+INSERT INTO gin_check_jsonb values ('{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
+INSERT INTO gin_check_jsonb values ('[[14,2,3]]');
+INSERT INTO gin_check_jsonb values ('[1,[14,2,3]]');
+CREATE INDEX "gin_check_jsonb_idx" on gin_check_jsonb USING GIN("j" jsonb_path_ops);
+SELECT gin_index_check('gin_check_jsonb_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_jsonb;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index bbd9b9f8281..92ddbbc7a89 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -38,3 +38,15 @@ SELECT gin_index_check('gin_check_text_array_idx');
 
 -- cleanup
 DROP TABLE gin_check_text_array;
+
+-- Test GIN over jsonb
+CREATE TABLE "gin_check_jsonb"("j" jsonb);
+INSERT INTO gin_check_jsonb values ('{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
+INSERT INTO gin_check_jsonb values ('[[14,2,3]]');
+INSERT INTO gin_check_jsonb values ('[1,[14,2,3]]');
+CREATE INDEX "gin_check_jsonb_idx" on gin_check_jsonb USING GIN("j" jsonb_path_ops);
+
+SELECT gin_index_check('gin_check_jsonb_idx');
+
+-- cleanup
+DROP TABLE gin_check_jsonb;
-- 
2.49.0

From 17562587b68a5d29245b4c7d852d0c29876ace54 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Fri, 28 Mar 2025 17:05:18 +0100
Subject: [PATCH v20250328 5/6] amcheck: Add a GIN index to the CREATE INDEX
 CONCURRENTLY tests

The existing CREATE INDEX CONCURRENTLY tests checking only B-Tree, but
can be cheaply extended to also check GIN. This helps increasing test
coverage for GIN amcheck, especially related to handling concurrent page
splits and posting list trees.

This already helped to identify several issues during development of the
GIN amcheck support.

Author: Mark Dilger <mark.dilger@enterprisedb.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Reviewed-By: Kirill Reshke <reshkekirill@gmail.com>
Discussion: https://postgr.es/m/BC221A56-977C-418E-A1B8-9EFC881D80C5%40enterprisedb.com
---
 contrib/amcheck/t/002_cic.pl     | 10 +++++---
 contrib/amcheck/t/003_cic_2pc.pl | 40 ++++++++++++++++++++++++++------
 2 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
index 0b6a5a9e464..6a0c4f61125 100644
--- a/contrib/amcheck/t/002_cic.pl
+++ b/contrib/amcheck/t/002_cic.pl
@@ -21,8 +21,9 @@ $node->append_conf('postgresql.conf',
 	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
 $node->start;
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
-$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 $node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i)));
+$node->safe_psql('postgres', q(CREATE INDEX ginidx ON tbl USING gin(j)));
 
 #
 # Stress CIC with pgbench.
@@ -40,13 +41,13 @@ $node->pgbench(
 	{
 		'002_pgbench_concurrent_transaction' => q(
 			BEGIN;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0, '{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
 			COMMIT;
 		  ),
 		'002_pgbench_concurrent_transaction_savepoints' => q(
 			BEGIN;
 			SAVEPOINT s1;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 			COMMIT;
 		  ),
 		'002_pgbench_concurrent_cic' => q(
@@ -54,7 +55,10 @@ $node->pgbench(
 			\if :gotlock
 				DROP INDEX CONCURRENTLY idx;
 				CREATE INDEX CONCURRENTLY idx ON tbl(i);
+				DROP INDEX CONCURRENTLY ginidx;
+				CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 				SELECT bt_index_check('idx',true);
+				SELECT gin_index_check('ginidx');
 				SELECT pg_advisory_unlock(42);
 			\endif
 		  )
diff --git a/contrib/amcheck/t/003_cic_2pc.pl b/contrib/amcheck/t/003_cic_2pc.pl
index 9134487f3b4..00a446a381f 100644
--- a/contrib/amcheck/t/003_cic_2pc.pl
+++ b/contrib/amcheck/t/003_cic_2pc.pl
@@ -25,7 +25,7 @@ $node->append_conf('postgresql.conf',
 	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
 $node->start;
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
-$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int, j jsonb)));
 
 
 #
@@ -41,7 +41,7 @@ my $main_h = $node->background_psql('postgres');
 $main_h->query_safe(
 	q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
 my $cic_h = $node->background_psql('postgres');
@@ -50,6 +50,7 @@ $cic_h->query_until(
 	qr/start/, q(
 \echo start
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $main_h->query_safe(
@@ -60,7 +61,7 @@ PREPARE TRANSACTION 'a';
 $main_h->query_safe(
 	q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '[[14,2,3]]');
 ));
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'a';));
@@ -69,7 +70,7 @@ $main_h->query_safe(
 	q(
 PREPARE TRANSACTION 'b';
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '"mary had a little lamb"');
 ));
 
 $node->safe_psql('postgres', q(COMMIT PREPARED 'b';));
@@ -86,6 +87,9 @@ $cic_h->quit;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after overlapping 2PC');
 
+$result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
+is($result, '0', 'gin_index_check after overlapping 2PC');
+
 
 #
 # Server restart shall not change whether prepared xact blocks CIC
@@ -94,7 +98,7 @@ is($result, '0', 'bt_index_check after overlapping 2PC');
 $node->safe_psql(
 	'postgres', q(
 BEGIN;
-INSERT INTO tbl VALUES(0);
+INSERT INTO tbl VALUES(0, '{"a":[["b",{"x":1}],["b",{"x":2}]],"c":3}');
 PREPARE TRANSACTION 'spans_restart';
 BEGIN;
 CREATE TABLE unused ();
@@ -108,12 +112,16 @@ $reindex_h->query_until(
 \echo start
 DROP INDEX CONCURRENTLY idx;
 CREATE INDEX CONCURRENTLY idx ON tbl(i);
+DROP INDEX CONCURRENTLY ginidx;
+CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
 ));
 
 $node->safe_psql('postgres', "COMMIT PREPARED 'spans_restart'");
 $reindex_h->quit;
 $result = $node->psql('postgres', q(SELECT bt_index_check('idx',true)));
 is($result, '0', 'bt_index_check after 2PC and restart');
+$result = $node->psql('postgres', q(SELECT gin_index_check('ginidx')));
+is($result, '0', 'gin_index_check after 2PC and restart');
 
 
 #
@@ -136,14 +144,14 @@ $node->pgbench(
 	{
 		'003_pgbench_concurrent_2pc' => q(
 			BEGIN;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0,'null');
 			PREPARE TRANSACTION 'c:client_id';
 			COMMIT PREPARED 'c:client_id';
 		  ),
 		'003_pgbench_concurrent_2pc_savepoint' => q(
 			BEGIN;
 			SAVEPOINT s1;
-			INSERT INTO tbl VALUES(0);
+			INSERT INTO tbl VALUES(0,'[false, "jnvaba", -76, 7, {"_": [1]}, 9]');
 			PREPARE TRANSACTION 'c:client_id';
 			COMMIT PREPARED 'c:client_id';
 		  ),
@@ -163,7 +171,25 @@ $node->pgbench(
 				SELECT bt_index_check('idx',true);
 				SELECT pg_advisory_unlock(42);
 			\endif
+		  ),
+		'005_pgbench_concurrent_cic' => q(
+			SELECT pg_try_advisory_lock(42)::integer AS gotginlock \gset
+			\if :gotginlock
+				DROP INDEX CONCURRENTLY ginidx;
+				CREATE INDEX CONCURRENTLY ginidx ON tbl USING gin(j);
+				SELECT gin_index_check('ginidx');
+				SELECT pg_advisory_unlock(42);
+			\endif
+		  ),
+		'006_pgbench_concurrent_ric' => q(
+			SELECT pg_try_advisory_lock(42)::integer AS gotginlock \gset
+			\if :gotginlock
+				REINDEX INDEX CONCURRENTLY ginidx;
+				SELECT gin_index_check('ginidx');
+				SELECT pg_advisory_unlock(42);
+			\endif
 		  )
+
 	});
 
 $node->stop;
-- 
2.49.0

From 5fccd4981c6aac5249bceca4b3e698d53f9a4480 Mon Sep 17 00:00:00 2001
From: Mark Dilger <mark.dilger@enterprisedb.com>
Date: Fri, 21 Feb 2025 12:11:07 -0800
Subject: [PATCH v20250328 6/6] Stress test verify_gin() using pgbench

Add a tap test which inserts, updates, deletes, and checks in
parallel.  Like all pgbench based tap tests, this test contains race
conditions between the operations, so Your Mileage May Vary.  For
me, on my laptop, I got failures like:

	index "ginidx" has wrong tuple order on entry tree page

which I have not yet investigated.  The test is included here for
anybody interested in debugging this failure.
---
 contrib/amcheck/t/006_gin_concurrency.pl | 196 +++++++++++++++++++++++
 1 file changed, 196 insertions(+)
 create mode 100644 contrib/amcheck/t/006_gin_concurrency.pl

diff --git a/contrib/amcheck/t/006_gin_concurrency.pl b/contrib/amcheck/t/006_gin_concurrency.pl
new file mode 100644
index 00000000000..afc67940d4d
--- /dev/null
+++ b/contrib/amcheck/t/006_gin_concurrency.pl
@@ -0,0 +1,196 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init;
+$node->append_conf('postgresql.conf',
+	'lock_timeout = ' . (1000 * $PostgreSQL::Test::Utils::timeout_default));
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i integer[], j jsonb, k jsonb)));
+$node->safe_psql('postgres', q(CREATE INDEX ginidx ON tbl USING gin(i, j, k)));
+$node->safe_psql('postgres', q(CREATE TABLE jsondata (i serial, j jsonb)));
+$node->safe_psql('postgres', q(INSERT INTO jsondata (j) VALUES
+	('1'),
+	('91'),
+	('[5]'),
+	('true'),
+	('"zxI"'),
+	('[1, 7]'),
+	('["", 4]'),
+	('"utDFBz"'),
+	('[[9], ""]'),
+	('"eCvxKPML"'),
+	('["1VMQNQM"]'),
+	('{"": "562c"}'),
+	('[58, 8, null]'),
+	('{"": {"": 62}}'),
+	('["", 6, 19, ""]'),
+	('{"ddfWTQ": true}'),
+	('["", 734.2, 9, 5]'),
+	('"GMV27mjtuuqmlltw"'),
+	('{"dabe": -5, "": 6}'),
+	('"hgihykirQGIYTcCA30"'),
+	('[9, {"Utrn": -6}, ""]'),
+	('"BJTZUMST1_WWEgyqgka_"'),
+	('["", -4, "", [-2], -47]'),
+	('{"": [3], "": {"": "y"}}'),
+	('{"myuijj": "YUWIUZXXLGS"}'),
+	('{"3": false, "C": "1sHTX"}'),
+	('"ZGUORVDE_ACF1QXJ_hipgwrks"'),
+	('{"072": [3, -4], "oh": "eL"}'),
+	('[{"de": 9, "JWHPMRZJW": [0]}]'),
+	('"EACJUZEBAFFBEE6706SZLWVGO635"'),
+	('["P", {"TZW": [""]}, {"": [0]}]'),
+	('{"": -6, "YMb": -22, "__": [""]}'),
+	('{"659": [8], "bfc": [0], "V": ""}'),
+	('{"8776": "1tryl", "Q": 2, "": 4.6}'),
+	('[[1], "", 9, 0, [1, 0], -1, 0, "C"]'),
+	('"635321pnpjlfFzhGTIYP9265iA_19D8260"'),
+	('"klmxsoCFDtzxrhotsqlnmvmzlcbdde34twj"'),
+	('"GZSXSZVS19ecbe_ZJJED0379c1j9_GSU9167"'),
+	('{"F18s": {"": -84194}, "ececab2": [""]}'),
+	('["", {"SVAvgg": "Q"}, 1, 9, "gypy", [1]]'),
+	('[[""], {"": 5}, "GVZGGVGSWM", 2, ["", 8]]'),
+	('{"V": 8, "TPNL": [826, null], "4": -9.729}'),
+	('{"HTJP_DAptxn6": 9, "": "r", "hji4124": ""}'),
+	('[1, ["9", 5, 6, ""], {"": "", "": "efb"}, 7]'),
+	('{"": 6, "1251e_cajrgkyzuxBEDM017444EFD": 548}'),
+	('{"853": -60, "TGLUG_jxmrggv": null, "pjx": ""}'),
+	('[0, "wsgnnvCfJVV_KOMLVXOUIS9FIQLPXXBbbaohjrpj"]'),
+	('"nizvkl36908OLW22ecbdeEBMHMiCEEACcikwkjpmu30X_m"'),
+	('{"bD24eeVZWY": 1, "Bt": 9, "": 6052, "FT": ["h"]}'),
+	('"CDBnouyzlAMSHJCtguxxizpzgkNYfaNLURVITNLYVPSNLYNy"'),
+	('{"d": [[4, "N"], null, 6, true], "1PKV": 6, "9": 6}'),
+	('[-7326, [83, 55], -63, [0, {"": 1}], {"ri0": false}]'),
+	('{"": 117.38, "FCkx3608szztpvjolomzvlyrshyvrgz": -4.2}'),
+	('["", 8, {"WXHNG": {"6": 4}}, [null], 7, 2, "", 299, 6]'),
+	('[[-992.2, "TPm", "", "cedeff79BD8", "t", [1]], 0, [-7]]'),
+	('[9, 34, ["LONuyiYGQZ"], [7, 88], ["c"], 1, 6, "", [[2]]]'),
+	('[20, 5, null, "eLHTXRWNV", 8, ["pnpvrum", -3], "FINY", 3]'),
+	('[{"": "", "b": 2, "d": "egu"}, "aPNK", 2, 9, {"": -79946}]'),
+	('[1, {"769": 9}, 5, 9821, 22, 0, 2.7, 5, 4, 191, 54.599, 24]'),
+	('["c", 77, "b_0lplvHJNLMxw", "VN76dhFadaafadfe5dfbco", false]'),
+	('"TYIHXebbPK_86QMP_199bEEIS__8205986vdC_CFAEFBFCEFCJQRHYoqztv"'),
+	('"cdmxxxzrhtxpwuyrxinmhb5577NSPHIHMTPQYTXSUVVGJPUUMCBEDb_1569e"'),
+	('[[5, null, "C"], "ORNR", "mnCb", 1, -800, "6953", ["K", 0], ""]'),
+	('"SSKLTHJxjxywwquhiwsde353eCIJJjkyvn9946c2cdVadcboiyZFAYMHJWGMMT"'),
+	('"5185__D5AtvhizvmEVceF3jxtghlCF0789_owmsztJHRMOJ7rlowxqq51XLXJbF"'),
+	('{"D": 565206, "xupqtmfedff": "ZGJN9", "9": 1, "glzv": -47, "": -8}'),
+	('{"": 9, "": {"": [null], "ROP": 842}, "": ["5FFD", 7, 5, 1, 94, 1]}'),
+	('{"JLn": ["8s"], "": "_ahxizrzhivyzvhr", "XSAt": 5, "P": 2838, "": 5}'),
+	('[51, 3, {"": 9, "": -9, "": [[6]]}, 7, 7, {"": 0}, "TXLQL", 7.6, [7]]'),
+	('[-38.7, "kre40", 5, {"": null}, "tvuv", 8, "", "", "uizygprwwvh", "1"]'),
+	('"z934377_nxmzjnuqglgyukjteefeihjyot1irkvwnnrqinptlpzwjgmkjbQMUVxxwvbdz"'),
+	('[165.9, "dAFD_60JQPYbafh", false, {"": 6, "": "fcfd"}, [[2], "c"], 4, 2]'),
+	('"ffHOOPVSSACDqiyeecTNWJMWPNRXU283aHRXNUNZZZQPUGYSQTTQXQVJM5eeafcIPGIHcac"'),
+	('[2, 8, -53, {"": 5}, "F9", 8, "SGUJPNVI", "7OLOZH", 9.84, {"": 6}, 207, 6]'),
+	('"xqmqmyljhq__ZGWJVNefagsxrsktruhmlinhxloupuVQW0804901NKGGMNNSYYXWQOosz8938"'),
+	('{"FEoLfaab1160167": {"L": [42, 0]}, "938": "FCCUPGYYYMQSQVZJKM", "knqmk": 2}'),
+	('"0igyurmOMSXIYHSZQEAcxlvgqdxkhwtrbaabfaaMC138Z_BDRLrythpi30_MPRXMTOILRLswmoy"'),
+	('"1129BBCABFFAACA9VGVKipnwohaccc9TSIMTOQKHmcGYVeFE_PWKLHmpyj60137672qugtsstugg"'),
+	('"D3BDA069074174vx48A37IVHWVXLUP9382542ypsl1465pixtryzCBgrkkhrvCC_BDDFatkyXHLIe"'),
+	('[{"esx7": -53, "ec60834YGVMYoXAAvgxmmqnojyzmiklhdovFipl": 2, "os": 66433}, 9.13]'),
+	('{"": ["", 4, null, 5, null], "": "3", "5_GMMHTIhPB_F_vsebc1": "Er", "GY": 121.32}'),
+	('["krTVPYDEd", 5, 8, [6, -6], [[-9], 3340, [[""]]], "", 5, [6, true], 3, "", 1, ""]'),
+	('{"rBNPKN8446080wruOLeceaCBDCKWNUYYMONSJUlCDFExr": {"": "EE0", "6826": 5, "": 7496}}'),
+	('[3, {"": -8}, "101dboMVSNKZLVPITLHLPorwwuxxjmjsh", "", "LSQPRVYKWVYK945imrh", 4, 51]'),
+	('[["HY6"], "", "bcdB", [2, [85, 1], 3, 3, 3, [8]], "", ["_m"], "2", -33, 8, 3, "_xwj"]'),
+	('["", 0, -3.7, 8, false, null, {"": 5}, 9, "06FccxFcdb283bbZGGVRSMWLJH2_PBAFpwtkbceto"]'),
+	('[52, "", -39, -7, [1], "c", {"": 9, "": 45528, "G": {"": 7}}, 3, false, 0, "EB", 8, -6]'),
+	('"qzrkvrlG78CCCEBCptzwwok808805243QXVSYed3efZSKLSNXPxhrS357KJMWSKgrfcFFDFDWKSXJJSIJ_yqJu"'),
+	('[43, 8, {"": ""}, "uwtv__HURKGJLGGPPW", 9, 66, "yqrvghxuw", {"J": false}, false, 2, 0, 4]'),
+	('[{"UVL": 7, "": 1}, false, [6, "H"], "boxlgqgm", 3, "znhm", [true], 0, ["e", 3.7], 9, 9.4]'),
+	('{"825634870117somzqw": 1, "": [5], "gYH": "_XT", "b22412631709RZP": 3, "": "", "FDB": [""]}'),
+	('[8, ["_bae"], "", "WN", 80, {"o": 2, "aff": 16}, false, true, 4, 6, {"nutzkzikolsxZRQ": 30}]'),
+	('["588BD9c_xzsn", {"k": 0, "_Ecezlkslrwvjpwrukiqzl": 3, "Ej": "4"}, "TUXwghn1dTNRXJZpswmD", 5]'),
+	('[{"dC": 7}, {"": 1, "4": 41, "": "", "": "adKS"}, {"": "ypv"}, 6, 9, 2, [-61.46], [1, 3.9], 2]'),
+	('{"8": 8, "": -364, "855": -238.1, "zj": 9, "SNHJG413": 3, "UMNVI73": [60, 0], "iwvqse": -1.833}'),
+	('"VTUKMLZKQPHIEniCFZ_cjrhvspxzulvxhqykjzmrw89OGOGISWdcrvpOPLOFALGK809896999xzqnkm63254_xrmcfcedb"'),
+	('["", "USNQbcexyFDCdBAFWJIphloxwytplyZZR008400FmoiYXVYOHVGV79795644463Aug_aeoDDEjzoziisxoykuijhz"]'),
+	('{"": 1, "5abB58gXVQVTTMWU3jSHXMMNV": "", "nv": 934, "kjsnhtj": 8, "": [{"xm": [71, 425]}], "": -9}'),
+	('"__oliqCcbwwyqmtECsqivplcb1NTMOQRZTYRJONOIPWNHKWLJRIHKROMJNZLNGTTKRcedebccdbMTQXSzhynxmllqxuhnxBA_"'),
+	('["thgACBWGNGMkFFEA", [0, -1349, {"18": "RM", "F3": 6, "dP": "_AF"}, 64, 0, {"f": [8]}], 5, [[0]], 2]')
+));
+
+#
+# Stress gin with pgbench.
+#
+# Modify the table data, and hence the index data, from multiple process
+# while from other processes run the index checking code.  This should,
+# if the index is large enough, result in the checks performing across
+# concurrent page splits.
+#
+$node->pgbench(
+	'--no-vacuum --client=20 --transactions=5000',
+	0,
+	[qr{actually processed}],
+	[qr{^$}],
+	'concurrent DML and index checking',
+	{
+		'006_gin_concurrency_insert_1' => q(
+			INSERT INTO tbl (i, j, k)
+				(SELECT ARRAY[x.i, y.i, random(0,100000), random(0,100000)], x.j, y.j
+					FROM jsondata x, jsondata y
+					WHERE x.i = random(1,100)
+					  AND y.i = random(1,100)
+				)
+		  ),
+		'006_gin_concurrency_insert_2' => q(
+			INSERT INTO tbl (i, j, k)
+				(SELECT gs.i, j.j, j.j || j.j
+					FROM jsondata j,
+						 (SELECT array_agg(gs) AS i FROM generate_series(random(0,100), random(101,200)) gs) gs
+					WHERE j.i = random(1,100)
+				)
+		  ),
+		'006_gin_concurrency_insert_nulls' => q(
+			INSERT INTO tbl (i, j, k) VALUES
+				(null,               null, null),
+				(null,               null, '[]'),
+				(null,               '[]', null),
+				(ARRAY[]::INTEGER[], null, null),
+				(null,               '[]', '[]'),
+				(ARRAY[]::INTEGER[], '[]', null),
+				(ARRAY[]::INTEGER[], '[]', '[]')
+		  ),
+		'006_gin_concurrency_update_i' => q(
+			UPDATE tbl
+				SET i = (SELECT i || i FROM tbl ORDER BY random() LIMIT 1)
+				WHERE j = (SELECT j FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_update_j' => q(
+			UPDATE tbl
+				SET j = (SELECT j || j FROM tbl ORDER BY random() LIMIT 1)
+				WHERE k = (SELECT k FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_update_k' => q(
+			UPDATE tbl
+				SET k = (SELECT k || k FROM tbl ORDER BY random() LIMIT 1)
+				WHERE i = (SELECT i FROM tbl ORDER BY random() LIMIT 1);
+		),
+		'006_gin_concurrency_delete' => q(
+			DELETE FROM tbl
+				WHERE random(1,5) = 3;
+		),
+		'006_gin_concurrency_gin_index_check' => q(
+				SELECT gin_index_check('ginidx');
+		)
+	});
+
+$node->stop;
+done_testing();
+
-- 
2.49.0

From 88b703737f112c177a3c1ed877bbb0a1374bb8ca Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Thu, 8 May 2025 19:54:38 +0300
Subject: [PATCH] verify gin fixes and tests

---
 contrib/amcheck/expected/check_gin.out |  12 ++
 contrib/amcheck/meson.build            |   1 +
 contrib/amcheck/sql/check_gin.sql      |  10 +
 contrib/amcheck/t/006_verify_gin.pl    | 274 +++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c           |  57 +++--
 5 files changed, 324 insertions(+), 30 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..3b6077c6282
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,274 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+        CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+        SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+        $$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+inconsistent_with_parent_key_parent_key_corrupted_test();
+inconsistent_with_parent_key_child_key_corrupted_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		"aaaaa",
+		"ccccc",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295');
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		"rrrrrrrrrr",
+		"zzzzzzzzzz",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295');
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[],b text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a,b);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $find = pack('s', 1) . pack('c', 0x09) . "aaa";
+	my $replace = pack('s', 2) . pack('c', 0x09) . "aaa";
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$find = pack('s', 2) . pack('c', 0x09) . "bbb";
+	$replace = pack('s', 1) . pack('c', 0x09) . "bbb";
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295');
+}
+
+sub inconsistent_with_parent_key_parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		"aaaaaaaaaa",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has inconsistent records on page 5 offset 3');
+}
+
+sub inconsistent_with_parent_key_child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 5;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		"pppppppppp",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has inconsistent records on page 5 offset 3');
+}
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+sub string_replace_block {
+	my ($filename, $find, $replace, $blksize, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/$replace/g;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
@@ -463,17 +459,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +525,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +551,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +577,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +586,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
@@ -608,10 +605,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -749,7 +746,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.43.0

From 973de3eaeeca7ff2946a5b0f92f481d70ba5b78d Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 26 May 2025 12:10:37 +0200
Subject: [PATCH v2 1/2] verify gin fixes and tests

---
 contrib/amcheck/expected/check_gin.out |  12 ++
 contrib/amcheck/meson.build            |   1 +
 contrib/amcheck/sql/check_gin.sql      |  10 +
 contrib/amcheck/t/006_verify_gin.pl    | 274 +++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c           |  57 +++--
 5 files changed, 324 insertions(+), 30 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..3b6077c6282
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,274 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+        CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+        SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+        $$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+inconsistent_with_parent_key_parent_key_corrupted_test();
+inconsistent_with_parent_key_child_key_corrupted_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		"aaaaa",
+		"ccccc",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295');
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		"rrrrrrrrrr",
+		"zzzzzzzzzz",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295');
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[],b text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a,b);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $find = pack('s', 1) . pack('c', 0x09) . "aaa";
+	my $replace = pack('s', 2) . pack('c', 0x09) . "aaa";
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$find = pack('s', 2) . pack('c', 0x09) . "bbb";
+	$replace = pack('s', 1) . pack('c', 0x09) . "bbb";
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295');
+}
+
+sub inconsistent_with_parent_key_parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		"aaaaaaaaaa",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has inconsistent records on page 5 offset 3');
+}
+
+sub inconsistent_with_parent_key_child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blksize = 8192;
+	my $blkno = 5;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		"pppppppppp",
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ 'index "test_gin_idx" has inconsistent records on page 5 offset 3');
+}
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+sub string_replace_block {
+	my ($filename, $find, $replace, $blksize, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/$replace/g;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
@@ -463,17 +459,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +525,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +551,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +577,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +586,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
@@ -608,10 +605,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -749,7 +746,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.49.0

From 1495281bb00810ed3c5c3ea20bbb3b626c73b580 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 26 May 2025 12:24:21 +0200
Subject: [PATCH v2 2/2] undo

---
 contrib/amcheck/verify_gin.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 427cf1669a6..8f6a5410cb7 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,10 +359,14 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * The rightmost parent key is always invalid item pointer.
-				 * Its value is 'Infinity' and not explicitly stored.
+				 * Set rightmost parent key to invalid item pointer. Its value
+				 * is 'Infinity' and not explicitly stored.
 				 */
-				ptr->parentkey = posting_item->key;
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
+					ptr->parentkey = posting_item->key;
+
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.49.0

From 2aeb21a7fc029d823e55f861344ee613b295e912 Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Thu, 29 May 2025 14:33:37 +0300
Subject: [PATCH v3 2/2] undo

---
 contrib/amcheck/verify_gin.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 427cf1669a6..8f6a5410cb7 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,10 +359,14 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * The rightmost parent key is always invalid item pointer.
-				 * Its value is 'Infinity' and not explicitly stored.
+				 * Set rightmost parent key to invalid item pointer. Its value
+				 * is 'Infinity' and not explicitly stored.
 				 */
-				ptr->parentkey = posting_item->key;
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
+					ptr->parentkey = posting_item->key;
+
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.43.0

From 27d54e5bc4cf37b429543969c881a5d1d7fabc26 Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Thu, 29 May 2025 13:47:47 +0300
Subject: [PATCH v3 1/2] verify-gin-fixes-and-tests

---
 contrib/amcheck/expected/check_gin.out |  12 +
 contrib/amcheck/meson.build            |   1 +
 contrib/amcheck/sql/check_gin.sql      |  10 +
 contrib/amcheck/t/006_verify_gin.pl    | 313 +++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c           |  57 +++--
 5 files changed, 363 insertions(+), 30 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..5d974228644
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,313 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+my $blksize;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+        CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+        SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+        $$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+inconsistent_with_parent_key__parent_key_corrupted_test();
+inconsistent_with_parent_key__child_key_corrupted_test();
+inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		"aaaaa",
+		'"ccccc"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		"rrrrrrrrrr",
+		'"zzzzzzzzzz"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[],b text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a,b);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $attrno_1 = pack('s', 1);
+	my $attrno_2 = pack('s', 2);
+
+	my $find = qr/($attrno_1)(.)(aaa)/s;
+	my $replace = '"' . $attrno_2 . '$2$3"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$find = qr/($attrno_2)(.)(bbb)/s;
+	$replace = '"' . $attrno_1 . '$2$3"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub inconsistent_with_parent_key__parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		'"aaaaaaaaaa"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
+}
+
+sub inconsistent_with_parent_key__child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 5;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		'"pppppppppp"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
+}
+
+sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 2;  # posting tree root
+
+	# we have a posting tree for 'aaaaa' key with the root at 2nd block
+	# and two leaf pages 3 and 4. for 4th page high key is (65,52), so let's make it a little bit
+	# smaller, so that there are tid's in leaf page that are larger then the new high key.
+	my $find = pack('S', 65) . pack('S', 52);
+	my $replace = '"' . pack('S', 64) . pack('S', 52) . '"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\": tid exceeds parent's high key in postingTree leaf on block 4");
+}
+
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+sub string_replace_block {
+	my ($filename, $find, $replace, $blksize, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/$replace/gee;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
@@ -463,17 +459,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +525,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +551,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +577,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +586,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
@@ -608,10 +605,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -749,7 +746,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.43.0

From f24396e4cbfa5d5b64cb815654a50bbd9d003154 Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Thu, 29 May 2025 13:47:47 +0300
Subject: [PATCH v4 1/3] verify-gin-fixes-and-tests

---
 contrib/amcheck/expected/check_gin.out |  12 +
 contrib/amcheck/meson.build            |   1 +
 contrib/amcheck/sql/check_gin.sql      |  10 +
 contrib/amcheck/t/006_verify_gin.pl    | 313 +++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c           |  57 +++--
 5 files changed, 363 insertions(+), 30 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..5d974228644
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,313 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+my $blksize;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+        CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+        SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+        $$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+inconsistent_with_parent_key__parent_key_corrupted_test();
+inconsistent_with_parent_key__child_key_corrupted_test();
+inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		"aaaaa",
+		'"ccccc"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		"rrrrrrrrrr",
+		'"zzzzzzzzzz"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[],b text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a,b);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $attrno_1 = pack('s', 1);
+	my $attrno_2 = pack('s', 2);
+
+	my $find = qr/($attrno_1)(.)(aaa)/s;
+	my $replace = '"' . $attrno_2 . '$2$3"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$find = qr/($attrno_2)(.)(bbb)/s;
+	$replace = '"' . $attrno_1 . '$2$3"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub inconsistent_with_parent_key__parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		'"aaaaaaaaaa"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
+}
+
+sub inconsistent_with_parent_key__child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+	 	CREATE TABLE $relname (a text[]);
+	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 5;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		'"pppppppppp"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
+}
+
+sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 2;  # posting tree root
+
+	# we have a posting tree for 'aaaaa' key with the root at 2nd block
+	# and two leaf pages 3 and 4. for 4th page high key is (65,52), so let's make it a little bit
+	# smaller, so that there are tid's in leaf page that are larger then the new high key.
+	my $find = pack('S', 65) . pack('S', 52);
+	my $replace = '"' . pack('S', 64) . pack('S', 52) . '"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\": tid exceeds parent's high key in postingTree leaf on block 4");
+}
+
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+sub string_replace_block {
+	my ($filename, $find, $replace, $blksize, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/$replace/gee;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
\ No newline at end of file
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
@@ -463,17 +459,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +525,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +551,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +577,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +586,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
@@ -608,10 +605,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -749,7 +746,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.49.0

From accb47ff16f06de2dc45524a1cf1223cefb93272 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Sun, 8 Jun 2025 22:29:31 +0200
Subject: [PATCH v4 2/3] whitespace fixes

---
 contrib/amcheck/t/006_verify_gin.pl | 69 +++++++++++++++--------------
 1 file changed, 35 insertions(+), 34 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index 5d974228644..e8afeb038fc 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -23,9 +23,9 @@ $blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
 $node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
 $node->safe_psql(
 	'postgres', q(
-        CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
-        SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
-        $$ LANGUAGE SQL;));
+		CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+		SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+		$$ LANGUAGE SQL;));
 
 # Tests
 invalid_entry_order_leaf_page_test();
@@ -43,8 +43,8 @@ sub invalid_entry_order_leaf_page_test
 	$node->safe_psql(
 		'postgres', qq(
 		DROP TABLE IF EXISTS $relname;
-	 	CREATE TABLE $relname (a text[]);
-	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
 		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
 		SELECT gin_clean_pending_list('$indexname');
 	 ));
@@ -77,18 +77,18 @@ sub invalid_entry_order_inner_page_test
 	$node->safe_psql(
 		'postgres', qq(
 		DROP TABLE IF EXISTS $relname;
-	 	CREATE TABLE $relname (a text[]);
-	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
 		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
 		SELECT gin_clean_pending_list('$indexname');
-	 ));
+	));
 	my $relpath = relation_filepath($indexname);
 
 	$node->stop;
@@ -118,11 +118,11 @@ sub invalid_entry_columns_order_test
 	$node->safe_psql(
 		'postgres', qq(
 		DROP TABLE IF EXISTS $relname;
-	 	CREATE TABLE $relname (a text[],b text[]);
-	 	CREATE INDEX $indexname ON $relname USING gin (a,b);
+		CREATE TABLE $relname (a text[],b text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a,b);
 		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
 		SELECT gin_clean_pending_list('$indexname');
-	 ));
+	));
 	my $relpath = relation_filepath($indexname);
 
 	$node->stop;
@@ -169,15 +169,15 @@ sub inconsistent_with_parent_key__parent_key_corrupted_test
 	$node->safe_psql(
 		'postgres', qq(
 		DROP TABLE IF EXISTS $relname;
-	 	CREATE TABLE $relname (a text[]);
-	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
 		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
 		SELECT gin_clean_pending_list('$indexname');
-	 ));
+	));
 	my $relpath = relation_filepath($indexname);
 
 	$node->stop;
@@ -207,13 +207,13 @@ sub inconsistent_with_parent_key__child_key_corrupted_test
 	$node->safe_psql(
 		'postgres', qq(
 		DROP TABLE IF EXISTS $relname;
-	 	CREATE TABLE $relname (a text[]);
-	 	CREATE INDEX $indexname ON $relname USING gin (a);
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
 		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
-        INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
 		SELECT gin_clean_pending_list('$indexname');
 	 ));
 	my $relpath = relation_filepath($indexname);
@@ -248,7 +248,7 @@ sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
 		CREATE TABLE $relname (a text[]);
 		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
 		CREATE INDEX $indexname ON $relname USING gin (a);
-	 ));
+	));
 	my $relpath = relation_filepath($indexname);
 
 	$node->stop;
@@ -287,7 +287,8 @@ sub relation_filepath
 	return "$pgdata/$rel";
 }
 
-sub string_replace_block {
+sub string_replace_block
+{
 	my ($filename, $find, $replace, $blksize, $blkno) = @_;
 
 	my $fh;
@@ -310,4 +311,4 @@ sub string_replace_block {
 	return;
 }
 
-done_testing();
\ No newline at end of file
+done_testing();
-- 
2.49.0

From e7d488efd2b93ad56573fa597f2134df6e48b0ea Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Thu, 29 May 2025 14:33:37 +0300
Subject: [PATCH v4 3/3] undo

---
 contrib/amcheck/verify_gin.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 427cf1669a6..8f6a5410cb7 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
+				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,10 +359,14 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * The rightmost parent key is always invalid item pointer.
-				 * Its value is 'Infinity' and not explicitly stored.
+				 * Set rightmost parent key to invalid item pointer. Its value
+				 * is 'Infinity' and not explicitly stored.
 				 */
-				ptr->parentkey = posting_item->key;
+				if (rightlink == InvalidBlockNumber)
+					ItemPointerSetInvalid(&ptr->parentkey);
+				else
+					ptr->parentkey = posting_item->key;
+
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.49.0

From f967749e3021e2c3b5c2680275f35aa6d428abf9 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:45:56 +0200
Subject: [PATCH v5 3/4] patch 2: gin_check_parent_keys_consistency

1) When we add new items to the entry tree stack, ptr->parenttup is always null
because GinPageGetOpaque(page)->rightlink is never NULL.

             /* last tuple in layer has no high key */
                if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
                    ptr->parenttup = CopyIndexTuple(idxtuple);
                else
                    ptr->parenttup = NULL;

Right way to check if entry doesn't have right neighbour is

            GinPageGetOpaque(page)->rightlink == InvalidBlockNumber

But even if we fix it, the condition would not do what the comment
says. If we want to have NULL as parenttup
only for the last tuple of the btree layer, the right check would be:

                if (i == maxoff && rightlink == InvalidBlockNumber)
                    ptr->parenttup = NULL;
             else
                    ptr->parenttup = CopyIndexTuple(idxtuple);

8) In the function gin_refind_parent() the code

                if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)

triggers Assert(ItemPointerIsValid(pointer)) within the
ItemPointerGetBlockNumber(), because itup->t_tid could be invalid.
AFAIS GIN code uses a special method GinGetDownlink(itup) that avoids
this Assert. So we can use it here too.

Please find the attached patch with fixes for issues above. Also there
are added regression test for multicolumn index,
and several tap tests with some basic corrupted index cases. I'm not
sure if it's the right way to write such tests and would
be glad to hear any feedback, especially about
invalid_entry_columns_order_test() where it seems important to
preserve
byte ordering. Also all tests expect standard page size 8192 now.
---
 contrib/amcheck/t/006_verify_gin.pl | 78 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  8 +--
 2 files changed, 82 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index 8c5975d2e37..a999a13d183 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -31,6 +31,8 @@ $node->safe_psql(
 invalid_entry_order_leaf_page_test();
 invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
+inconsistent_with_parent_key__parent_key_corrupted_test();
+inconsistent_with_parent_key__child_key_corrupted_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -158,6 +160,82 @@ sub invalid_entry_columns_order_test
 	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		'"aaaaaaaaaa"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
+}
+
+sub inconsistent_with_parent_key__child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 5;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		"nnnnnnnnnn",
+		'"pppppppppp"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
+}
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 26b98571b56..8f6a5410cb7 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -609,10 +609,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -750,7 +750,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.49.0

From 3f19acdaaeaa7db51ef66adf58befc5598339683 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:46:13 +0200
Subject: [PATCH v5 4/4] patch 3:
 gin_check_posting_tree_parent_keys_consistency

6) In posting tree parent key check part:

              /*
              * Check if this tuple is consistent with the downlink in the
              * parent.
              */
             if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
                ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
                ereport(ERROR,
                      ...
Here we don't check if stack->parentkey is valid, so sometimes we
compare invalid parentkey (because we can have
valid parentblk and invalid parentkey the same time). Invalid
parentkey is always bigger, so the code never triggers
ereport, but it doesn't look right. so probably we can rewrite it this way:

                if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
                ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)

7) When producing stack entries for posting tree check, we set parent
key like this:

             /*
              * Set rightmost parent key to invalid item pointer. Its value
              * is 'Infinity' and not explicitly stored.
              */
             if (rightlink == InvalidBlockNumber)
                ItemPointerSetInvalid(&ptr->parentkey);
             else
                ptr->parentkey = posting_item->key;

We set invalid parent key for all items of the rightmost page. But
it's the only rightmost item that doesn't have an explicit
parentkey (actually the comment says exactly this, but the code does a
different thing). All others have an explicit parent
key and we can set it. So fix can look like this:

                if (rightlink == InvalidBlockNumber && i == maxoff)
                ItemPointerSetInvalid(&ptr->parentkey);
             else
                ptr->parentkey = posting_item->key;

But for (rightlink == InvalidBlockNumber && i == maxoff)
posting_item->key is always (0,0) (we check it a little bit earlier),
so I think we can simplify it:

                ptr->parentkey = posting_item->key;
---
 contrib/amcheck/t/006_verify_gin.pl | 39 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        | 12 +++------
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index a999a13d183..e8afeb038fc 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -33,6 +33,7 @@ invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
 inconsistent_with_parent_key__parent_key_corrupted_test();
 inconsistent_with_parent_key__child_key_corrupted_test();
+inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -236,6 +237,44 @@ sub inconsistent_with_parent_key__child_key_corrupted_test
 	ok($stderr =~ "index \"$indexname\" has inconsistent records on page 5 offset 3");
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 2;  # posting tree root
+
+	# we have a posting tree for 'aaaaa' key with the root at 2nd block
+	# and two leaf pages 3 and 4. for 4th page high key is (65,52), so let's make it a little bit
+	# smaller, so that there are tid's in leaf page that are larger then the new high key.
+	my $find = pack('S', 65) . pack('S', 52);
+	my $replace = '"' . pack('S', 64) . pack('S', 52) . '"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\": tid exceeds parent's high key in postingTree leaf on block 4");
+}
+
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 8f6a5410cb7..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.49.0

From e90dd32a4260c9ecb7aa5584de5d7f393ac2729b Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:42:52 +0200
Subject: [PATCH v5 1/4] amcheck: Add gin_index_check on a multicolumn index

Extend the amcheck regression tests with a gin_index_check() check on
a small multicolumn index.

TODO briefly explain this increases test coverage

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/expected/check_gin.out | 12 ++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 10 ++++++++++
 2 files changed, 22 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
-- 
2.49.0

From 7e6913007e00d8f8a6f01f87972492e3c2a925a3 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:44:59 +0200
Subject: [PATCH v5 2/4] patch 1: gin_check_parent_keys_consistency

2) Check don't use attnum in comparisons, but for multicolumn indexes
attnum defines order. When we compare max entry page key
with parent key we ignore attnum. It means we occasionally can try to
compare keys of different columns.
While checking order within the same page we skip checking order for
tuples with different attnums now,
but it can be checked. Fix is easy: using ginCompareAttEntries()
instead of ginCompareEntries().

3) Here a code of the split detection

       if (rightlink != InvalidBlockNumber &&
             ginCompareEntries(&state, attnum, page_max_key,
                           page_max_key_category, parent_key,
                           parent_key_category) > 0)
          {
             /* split page detected, install right link to the stack */

Condition seems not right, because the child page max item key never
can be bigger then parent key.
It can be equal to the parentkey, and it means that there was no split
and the parent key that we cached in the stack is still
relevant. Or it could be less then cached parent key and it means that
split took place and old max item key moved to the
right neighbour and current page max item key should be less then
cached parent key. So I think we should replace > with <.

4) Here is the code for checking the order within the entry page.

           /*
           * First block is metadata, skip order check. Also, never check
           * for high key on rightmost page, as this key is not really
           * stored explicitly.
           *
           * Also make sure to not compare entries for different attnums,
           * which may be stored on the same page.
           */
          if (i != FirstOffsetNumber && attnum == prev_attnum &&
stack->blkno != GIN_ROOT_BLKNO &&
             !(i == maxoff && rightlink == InvalidBlockNumber))
          {
             prev_key = gintuple_get_key(&state, prev_tuple,
&prev_key_category);
             if (ginCompareEntries(&state, attnum, prev_key,
                              prev_key_category, current_key,
                              current_key_category) >= 0)

We skip checking the order for the root page, it's not clear why.
Probably there is some mess with the meta page, because
comment says "First block is metadata, skip order check". So I think
we can remove

                    stack->blkno != GIN_ROOT_BLKNO

5) The same place as 4). We skip checking the order for the high key
on the rightmost page, as this key is not really stored explicitly,
but for leaf pages all keys are stored explicitly, so we can check the
order for the last item of the leaf page too.
So I think we can change the condition to this:

            !(i == maxoff && rightlink == InvalidBlockNumber &&
!GinPageIsLeaf(page))

11) When we compare entry tree max page key with parent key:

             if (ginCompareAttEntries(&state, attnum, current_key,
                              current_key_category, parent_key_attnum,
                                      parent_key, parent_key_category) > 0)
             {
                /*
                 * There was a discrepancy between parent and child
                 * tuples. We need to verify it is not a result of
                 * concurrent call of gistplacetopage(). So, lock parent
                 * and try to find downlink for current page. It may be
                 * missing due to concurrent page split, this is OK.
                 */
                pfree(stack->parenttup);
                stack->parenttup = gin_refind_parent(rel, stack->parentblk,
                                            stack->blkno, strategy);

I think we can remove gin_refind_parent() and do ereport right away here.
The same logic as with 3). AFAIK it's impossible to have a child item
with a key that is higher than the cached parent key.
Parent key bounds what keys we can insert into the child page, so it
seems there is no way how they can appear there.
---
 contrib/amcheck/meson.build         |   1 +
 contrib/amcheck/t/006_verify_gin.pl | 197 ++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  37 +++---
 3 files changed, 217 insertions(+), 18 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..8c5975d2e37
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,197 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+my $blksize;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+		CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+		SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+		$$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		"aaaaa",
+		'"ccccc"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		"rrrrrrrrrr",
+		'"zzzzzzzzzz"',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[],b text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a,b);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $attrno_1 = pack('s', 1);
+	my $attrno_2 = pack('s', 2);
+
+	my $find = qr/($attrno_1)(.)(aaa)/s;
+	my $replace = '"' . $attrno_2 . '$2$3"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$find = qr/($attrno_2)(.)(bbb)/s;
+	$replace = '"' . $attrno_1 . '$2$3"';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	ok($stderr =~ "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295");
+}
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+sub string_replace_block
+{
+	my ($filename, $find, $replace, $blksize, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/$replace/gee;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..26b98571b56 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -463,17 +463,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +529,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +555,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +581,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +590,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
-- 
2.49.0

From 9e59d4fa552a998386be011b807fbe3329802fc0 Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:51:05 +0300
Subject: [PATCH 5/5] patch 4: remove unused parentlsn

This commit removes unused field parentlsn in gin_index_check()
---
 contrib/amcheck/verify_gin.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 427cf1669a6..f49e27b1a30 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -38,7 +38,6 @@ typedef struct GinScanItem
 	int			depth;
 	IndexTuple	parenttup;
 	BlockNumber parentblk;
-	XLogRecPtr	parentlsn;
 	BlockNumber blkno;
 	struct GinScanItem *next;
 } GinScanItem;
@@ -417,7 +416,6 @@ gin_check_parent_keys_consistency(Relation rel,
 	stack->depth = 0;
 	stack->parenttup = NULL;
 	stack->parentblk = InvalidBlockNumber;
-	stack->parentlsn = InvalidXLogRecPtr;
 	stack->blkno = GIN_ROOT_BLKNO;
 
 	while (stack)
@@ -428,7 +426,6 @@ gin_check_parent_keys_consistency(Relation rel,
 		OffsetNumber i,
 					maxoff,
 					prev_attnum;
-		XLogRecPtr	lsn;
 		IndexTuple	prev_tuple;
 		BlockNumber rightlink;
 
@@ -438,7 +435,6 @@ gin_check_parent_keys_consistency(Relation rel,
 									RBM_NORMAL, strategy);
 		LockBuffer(buffer, GIN_SHARE);
 		page = (Page) BufferGetPage(buffer);
-		lsn = BufferGetLSNAtomic(buffer);
 		maxoff = PageGetMaxOffsetNumber(page);
 		rightlink = GinPageGetOpaque(page)->rightlink;
 
@@ -481,7 +477,6 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr->depth = stack->depth;
 				ptr->parenttup = CopyIndexTuple(stack->parenttup);
 				ptr->parentblk = stack->parentblk;
-				ptr->parentlsn = stack->parentlsn;
 				ptr->blkno = rightlink;
 				ptr->next = stack->next;
 				stack->next = ptr;
@@ -611,7 +606,6 @@ gin_check_parent_keys_consistency(Relation rel,
 					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
-				ptr->parentlsn = lsn;
 				ptr->next = stack->next;
 				stack->next = ptr;
 			}
-- 
2.43.0

From a7dfd221a809ccd062fec36cd2b7acf025642bfb Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:39:13 +0300
Subject: [PATCH 3/5] patch 2: gin_check_parent_keys_consistency

This commit address issues with parent_key checks for the entry tree in gin_index_check():
- parenttup is always NULL. We want to set parenttup to NULL for the rightmost tuple of the level only, in all other cases it should be valid parent_key.
- use GinGetDownlink while retrieving child blkno to avoid triggering Assert (as core GIN code does).
---
 contrib/amcheck/t/006_verify_gin.pl | 80 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  8 +--
 2 files changed, 84 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index 46f693fbb08..fa6baa51546 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -31,6 +31,8 @@ $node->safe_psql(
 invalid_entry_order_leaf_page_test();
 invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
+inconsistent_with_parent_key__parent_key_corrupted_test();
+inconsistent_with_parent_key__child_key_corrupted_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -161,6 +163,84 @@ sub invalid_entry_columns_order_test
 	like($stderr, qr/$expected/);
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		'nnnnnnnnnn',
+		'aaaaaaaaaa',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has inconsistent records on page 5 offset 3";
+	like($stderr, qr/$expected/);
+}
+
+sub inconsistent_with_parent_key__child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 5;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		'nnnnnnnnnn',
+		'pppppppppp',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has inconsistent records on page 5 offset 3";
+	like($stderr, qr/$expected/);
+}
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 26b98571b56..8f6a5410cb7 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -609,10 +609,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -750,7 +750,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.43.0

From 33da75ed57ef66a47b59f0be8b7feeb6aaf2028e Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:42:52 +0200
Subject: [PATCH 1/5] amcheck: Add gin_index_check on a multicolumn index

This commit adds a regression test to verify that gin_index_check()
correctly handles multicolumn indexes, increases its test coverage.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/expected/check_gin.out | 12 ++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 10 ++++++++++
 2 files changed, 22 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
-- 
2.43.0

From e4a6292ff262e754c32fd26325bf386dec3a2981 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:44:59 +0200
Subject: [PATCH 2/5] patch 1: gin_check_parent_keys_consistency

This commit address several issues:
- Current code doesn't take into account attribute number when comparing index entries, but for multicolumn indexes attnum defines order.
- Add check that root page entries are ordered (there is nothing special about the root page that would prevent us from checking the order)
- Add checking order for the rightmost entry of the leaf level and skip it only for inner level.
- Split detection fix: in the case of a split, the cached parent key is greater than the current child key, not less.
---
 contrib/amcheck/meson.build         |   1 +
 contrib/amcheck/t/006_verify_gin.pl | 200 ++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  37 ++---
 3 files changed, 220 insertions(+), 18 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..46f693fbb08
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,200 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+my $blksize;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+		CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+		SELECT string_agg(substring('0123456789bcdfghjkmnpqrstvwxyz', ceil(random() * 30)::integer, 1), '') from generate_series(1, $1);
+		$$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		'aaaaa',
+		'ccccc',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string(1870) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string(1870) ||'}')::text[]);
+		SELECT gin_clean_pending_list('$indexname');
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		'rrrrrrrrrr',
+		'zzzzzzzzzz',
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[],b text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a,b);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		SELECT gin_clean_pending_list('$indexname');
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $attrno_1 = pack('s', 1);
+	my $attrno_2 = pack('s', 2);
+
+	my $find = qr/($attrno_1)(.)(aaa)/s;
+	my $replace = $attrno_2 . '$2$3';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$find = qr/($attrno_2)(.)(bbb)/s;
+	$replace = $attrno_1 . '$2$3';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+sub string_replace_block
+{
+	my ($filename, $find, $replace, $blksize, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/'"' . $replace . '"'/gee;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..26b98571b56 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -463,17 +463,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +529,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +555,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +581,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +590,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
-- 
2.43.0

From cb6f5b84e3bf5f5716c5470ffb4823563b23d21f Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:49:11 +0300
Subject: [PATCH 4/5] patch 3: gin_check_posting_tree_parent_keys_consistency

This commit address issues with parent_key checks for the posting tree in gin_index_check():
- Check if parentkey is valid before using it in the comparison. Checking that stack->parentblk is valid blocknum is not enough
- Set invalid parentkey for the rightmost child only, not for all children of the rightmost page.
---
 contrib/amcheck/t/006_verify_gin.pl | 40 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        | 12 +++------
 2 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index fa6baa51546..a7c7c1f5a61 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -33,6 +33,7 @@ invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
 inconsistent_with_parent_key__parent_key_corrupted_test();
 inconsistent_with_parent_key__child_key_corrupted_test();
+inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -241,6 +242,45 @@ sub inconsistent_with_parent_key__child_key_corrupted_test
 	like($stderr, qr/$expected/);
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 2;  # posting tree root
+
+	# we have a posting tree for 'aaaaa' key with the root at 2nd block
+	# and two leaf pages 3 and 4. replace 4th page's high key with (1,1)
+	# so that there are tid's in leaf page that are larger then the new high key.
+	my $find = pack('S*', 0, 4, 0) . '....';
+	my $replace = pack('S*', 0, 4, 0, 1, 1);
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blksize,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\": tid exceeds parent's high key in postingTree leaf on block 4";
+	like($stderr, qr/$expected/);
+}
+
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 8f6a5410cb7..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.43.0

From 64364caee85683f73818628decd066b33f01a7dd Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:44:59 +0200
Subject: [PATCH v7 2/5] patch 1: gin_check_parent_keys_consistency

This commit address several issues:
- Current code doesn't take into account attribute number when comparing index entries, but for multicolumn indexes attnum defines order.
- Add check that root page entries are ordered (there is nothing special about the root page that would prevent us from checking the order)
- Add checking order for the rightmost entry of the leaf level and skip it only for inner level.
- Split detection fix: in the case of a split, the cached parent key is greater than the current child key, not less.
---
 contrib/amcheck/meson.build         |   1 +
 contrib/amcheck/t/006_verify_gin.pl | 199 ++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  37 +++---
 3 files changed, 219 insertions(+), 18 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..e73c9d9f92e
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,199 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+my $blksize;
+
+# to get the split fast, we want tuples to be as large as possible, but the same time we don't want them to be toasted.
+my $filler_size = 1900;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+		CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+		SELECT string_agg(substring('0123456789abcdefghijklmnopqrstuvwxyz', ceil(random() * 36)::integer, 1), '') from generate_series(1, $1);
+		$$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		'aaaaa',
+		'ccccc',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	# to break the order in the inner page we need at least 3 items (rightmost key in the inner level is not checked for the order)
+	# so fill table until we have 2 splits
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string($filler_size) ||'}')::text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		'rrrrrrrrrr',
+		'zzzzzzzzzz',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[],b text[]);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		CREATE INDEX $indexname ON $relname USING gin (a,b);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $attrno_1 = pack('s', 1);
+	my $attrno_2 = pack('s', 2);
+
+	my $find = qr/($attrno_1)(.)(aaa)/s;
+	my $replace = $attrno_2 . '$2$3';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blkno
+	);
+
+	$find = qr/($attrno_2)(.)(bbb)/s;
+	$replace = $attrno_1 . '$2$3';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+# substitute pattern 'find' with 'replace' within the block with number 'blkno' in the file 'filename'
+sub string_replace_block
+{
+	my ($filename, $find, $replace, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/'"' . $replace . '"'/gee;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..26b98571b56 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -463,17 +463,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +529,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +555,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +581,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +590,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
-- 
2.43.0

From 79d67a965baca64e45cd9d08ef37576bfee43ff7 Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:39:13 +0300
Subject: [PATCH v7 3/5] patch 2: gin_check_parent_keys_consistency

This commit address issues with parent_key checks for the entry tree in gin_index_check():
- parenttup is always NULL. We want to set parenttup to NULL for the rightmost tuple of the level only, in all other cases it should be valid parent_key.
- use GinGetDownlink while retrieving child blkno to avoid triggering Assert (as core GIN code does).
---
 contrib/amcheck/t/006_verify_gin.pl | 78 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  8 +--
 2 files changed, 82 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index e73c9d9f92e..b997fc85f86 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -34,6 +34,8 @@ $node->safe_psql(
 invalid_entry_order_leaf_page_test();
 invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
+inconsistent_with_parent_key__parent_key_corrupted_test();
+inconsistent_with_parent_key__child_key_corrupted_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -159,6 +161,82 @@ sub invalid_entry_columns_order_test
 	like($stderr, qr/$expected/);
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	# fill the table until we have a split
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string($filler_size) ||'}')::text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		'nnnnnnnnnn',
+		'aaaaaaaaaa',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has inconsistent records on page 3 offset 3";
+	like($stderr, qr/$expected/);
+}
+
+sub inconsistent_with_parent_key__child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	# fill the table until we have a split
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string($filler_size) ||'}')::text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 3;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		'nnnnnnnnnn',
+		'pppppppppp',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has inconsistent records on page 3 offset 3";
+	like($stderr, qr/$expected/);
+}
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 26b98571b56..8f6a5410cb7 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -609,10 +609,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -750,7 +750,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.43.0

From b7b487b2d1dd97fbf6062674515711b9c2e4409e Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:49:11 +0300
Subject: [PATCH v7 4/5] patch 3:
 gin_check_posting_tree_parent_keys_consistency

This commit address issues with parent_key checks for the posting tree in gin_index_check():
- Check if parentkey is valid before using it in the comparison. Checking that stack->parentblk is valid blocknum is not enough
- Set invalid parentkey for the rightmost child only, not for all children of the rightmost page.
---
 contrib/amcheck/t/006_verify_gin.pl | 39 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        | 12 +++------
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index b997fc85f86..ff857aa9886 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -36,6 +36,7 @@ invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
 inconsistent_with_parent_key__parent_key_corrupted_test();
 inconsistent_with_parent_key__child_key_corrupted_test();
+inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -237,6 +238,44 @@ sub inconsistent_with_parent_key__child_key_corrupted_test
 	like($stderr, qr/$expected/);
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 2;  # posting tree root
+
+	# we have a posting tree for 'aaaaa' key with the root at 2nd block
+	# and two leaf pages 3 and 4. replace 4th page's high key with (1,1)
+	# so that there are tid's in leaf page that are larger then the new high key.
+	my $find = pack('S*', 0, 4, 0) . '....';
+	my $replace = pack('S*', 0, 4, 0, 1, 1);
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\": tid exceeds parent's high key in postingTree leaf on block 4";
+	like($stderr, qr/$expected/);
+}
+
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 8f6a5410cb7..427cf1669a6 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.43.0

From 4344b1b27a554139db20c3a1ba6f9250a577a45d Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:51:05 +0300
Subject: [PATCH v7 5/5] patch 4: remove unused parentlsn

This commit removes unused field parentlsn in gin_index_check()
---
 contrib/amcheck/verify_gin.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 427cf1669a6..f49e27b1a30 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -38,7 +38,6 @@ typedef struct GinScanItem
 	int			depth;
 	IndexTuple	parenttup;
 	BlockNumber parentblk;
-	XLogRecPtr	parentlsn;
 	BlockNumber blkno;
 	struct GinScanItem *next;
 } GinScanItem;
@@ -417,7 +416,6 @@ gin_check_parent_keys_consistency(Relation rel,
 	stack->depth = 0;
 	stack->parenttup = NULL;
 	stack->parentblk = InvalidBlockNumber;
-	stack->parentlsn = InvalidXLogRecPtr;
 	stack->blkno = GIN_ROOT_BLKNO;
 
 	while (stack)
@@ -428,7 +426,6 @@ gin_check_parent_keys_consistency(Relation rel,
 		OffsetNumber i,
 					maxoff,
 					prev_attnum;
-		XLogRecPtr	lsn;
 		IndexTuple	prev_tuple;
 		BlockNumber rightlink;
 
@@ -438,7 +435,6 @@ gin_check_parent_keys_consistency(Relation rel,
 									RBM_NORMAL, strategy);
 		LockBuffer(buffer, GIN_SHARE);
 		page = (Page) BufferGetPage(buffer);
-		lsn = BufferGetLSNAtomic(buffer);
 		maxoff = PageGetMaxOffsetNumber(page);
 		rightlink = GinPageGetOpaque(page)->rightlink;
 
@@ -481,7 +477,6 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr->depth = stack->depth;
 				ptr->parenttup = CopyIndexTuple(stack->parenttup);
 				ptr->parentblk = stack->parentblk;
-				ptr->parentlsn = stack->parentlsn;
 				ptr->blkno = rightlink;
 				ptr->next = stack->next;
 				stack->next = ptr;
@@ -611,7 +606,6 @@ gin_check_parent_keys_consistency(Relation rel,
 					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
-				ptr->parentlsn = lsn;
 				ptr->next = stack->next;
 				stack->next = ptr;
 			}
-- 
2.43.0

From 426895c13c77eab3e988a49da19434c0888323e0 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:42:52 +0200
Subject: [PATCH v7 1/5] amcheck: Add gin_index_check on a multicolumn index

This commit adds a regression test to verify that gin_index_check()
correctly handles multicolumn indexes, increases its test coverage.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/expected/check_gin.out | 12 ++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 10 ++++++++++
 2 files changed, 22 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
-- 
2.43.0

From cb24bb068582a39df9e9e59c2a9347889e896cf2 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:42:52 +0200
Subject: [PATCH v8 1/6] amcheck: Add gin_index_check on a multicolumn index

Adds a regression test with gin_index_check() on a multicolumn index,
to verify it's handled correctly and improve test coverage for code
introduced by 14ffaece0fb5.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/expected/check_gin.out | 12 ++++++++++++
 contrib/amcheck/sql/check_gin.sql      | 10 ++++++++++
 2 files changed, 22 insertions(+)

diff --git a/contrib/amcheck/expected/check_gin.out b/contrib/amcheck/expected/check_gin.out
index b4f0b110747..8dd01ced8d1 100644
--- a/contrib/amcheck/expected/check_gin.out
+++ b/contrib/amcheck/expected/check_gin.out
@@ -76,3 +76,15 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+SELECT gin_index_check('gin_check_multicolumn_idx');
+ gin_index_check 
+-----------------
+ 
+(1 row)
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
diff --git a/contrib/amcheck/sql/check_gin.sql b/contrib/amcheck/sql/check_gin.sql
index 66f42c34311..11caed3d6a8 100644
--- a/contrib/amcheck/sql/check_gin.sql
+++ b/contrib/amcheck/sql/check_gin.sql
@@ -50,3 +50,13 @@ SELECT gin_index_check('gin_check_jsonb_idx');
 
 -- cleanup
 DROP TABLE gin_check_jsonb;
+
+-- Test GIN multicolumn index
+CREATE TABLE "gin_check_multicolumn"(a text[], b text[]);
+INSERT INTO gin_check_multicolumn (a,b) values ('{a,c,e}','{b,d,f}');
+CREATE INDEX "gin_check_multicolumn_idx" on gin_check_multicolumn USING GIN(a,b);
+
+SELECT gin_index_check('gin_check_multicolumn_idx');
+
+-- cleanup
+DROP TABLE gin_check_multicolumn;
-- 
2.49.0

From 04b0c0c718dd109b9b4598d316b27daab281688d Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 9 Jun 2025 01:44:59 +0200
Subject: [PATCH v8 2/6] amcheck: Fix checks of entry order for GIN indexes

This tightens a couple checks in checking GIN indexes, which might have
resulted in incorrect results (false positives/negatives).

* The code skipped ordering checks if the entries were for different
  attributes (for multi-column GIN indexes), possibly missing some cases
  of data corruption. But the attribute number is part of the ordering,
  so we can check that.

* The root page was skipped when checking entry order, but that is
  unnecessary. The root page is subject to the same ordering rules, we
  can process it just like any other page.

* The high key on the right-most page was not checked, but that is
  needed only for inner pages (we don't store the high key for those).
  For leaf pages we can check the high key just fine.

* Correct the detection of split pages. If the page gets split, the
  cached parent key is creater than the current child key (not less, as
  the core incorrectly expected).

Issues reported by Arseniy Mikhin, along with a proposed patch. Review
by Andrey M. Borodin, cleanup and improvements by me.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/meson.build         |   1 +
 contrib/amcheck/t/006_verify_gin.pl | 199 ++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  37 +++---
 3 files changed, 219 insertions(+), 18 deletions(-)
 create mode 100644 contrib/amcheck/t/006_verify_gin.pl

diff --git a/contrib/amcheck/meson.build b/contrib/amcheck/meson.build
index b33e8c9b062..1f0c347ed54 100644
--- a/contrib/amcheck/meson.build
+++ b/contrib/amcheck/meson.build
@@ -49,6 +49,7 @@ tests += {
       't/003_cic_2pc.pl',
       't/004_verify_nbtree_unique.pl',
       't/005_pitr.pl',
+      't/006_verify_gin.pl',
     ],
   },
 }
diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
new file mode 100644
index 00000000000..7fdde170e06
--- /dev/null
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -0,0 +1,199 @@
+
+# Copyright (c) 2021-2025, PostgreSQL Global Development Group
+
+use strict;
+use warnings FATAL => 'all';
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More;
+
+my $node;
+my $blksize;
+
+# to get the split fast, we want tuples to be as large as possible, but the same time we don't want them to be toasted.
+my $filler_size = 1900;
+
+#
+# Test set-up
+#
+$node = PostgreSQL::Test::Cluster->new('test');
+$node->init(no_data_checksums => 1);
+$node->append_conf('postgresql.conf', 'autovacuum=off');
+$node->start;
+$blksize = int($node->safe_psql('postgres', 'SHOW block_size;'));
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql(
+	'postgres', q(
+		CREATE OR REPLACE FUNCTION  random_string( INT ) RETURNS text AS $$
+		SELECT string_agg(substring('0123456789abcdefghijklmnopqrstuvwxyz', ceil(random() * 36)::integer, 1), '') from generate_series(1, $1);
+		$$ LANGUAGE SQL;));
+
+# Tests
+invalid_entry_order_leaf_page_test();
+invalid_entry_order_inner_page_test();
+invalid_entry_columns_order_test();
+
+sub invalid_entry_order_leaf_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES ('{aaaaa,bbbbb}');
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# produce wrong order by replacing aaaaa with ccccc
+	string_replace_block(
+		$relpath,
+		'aaaaa',
+		'ccccc',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+sub invalid_entry_order_inner_page_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	# to break the order in the inner page we need at least 3 items (rightmost key in the inner level is not checked for the order)
+	# so fill table until we have 2 splits
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'pppppppppp' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'qqqqqqqqqq' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'rrrrrrrrrr' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'ssssssssss' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'tttttttttt' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'uuuuuuuuuu' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'vvvvvvvvvv' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'wwwwwwwwww' || random_string($filler_size) ||'}')::text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have rrrrrrrrr... and tttttttttt... as keys in the root, so produce wrong order by replacing rrrrrrrrrr....
+	string_replace_block(
+		$relpath,
+		'rrrrrrrrrr',
+		'zzzzzzzzzz',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+sub invalid_entry_columns_order_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[],b text[]);
+		INSERT INTO $relname (a,b) VALUES ('{aaa}','{bbb}');
+		CREATE INDEX $indexname ON $relname USING gin (a,b);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# mess column numbers
+	# root items order before: (1,aaa), (2,bbb)
+	# root items order after:  (2,aaa), (1,bbb)
+	my $attrno_1 = pack('s', 1);
+	my $attrno_2 = pack('s', 2);
+
+	my $find = qr/($attrno_1)(.)(aaa)/s;
+	my $replace = $attrno_2 . '$2$3';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blkno
+	);
+
+	$find = qr/($attrno_2)(.)(bbb)/s;
+	$replace = $attrno_1 . '$2$3';
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has wrong tuple order on entry tree page, block 1, offset 2, rightlink 4294967295";
+	like($stderr, qr/$expected/);
+}
+
+# Returns the filesystem path for the named relation.
+sub relation_filepath
+{
+	my ($relname) = @_;
+
+	my $pgdata = $node->data_dir;
+	my $rel = $node->safe_psql('postgres',
+		qq(SELECT pg_relation_filepath('$relname')));
+	die "path not found for relation $relname" unless defined $rel;
+	return "$pgdata/$rel";
+}
+
+# substitute pattern 'find' with 'replace' within the block with number 'blkno' in the file 'filename'
+sub string_replace_block
+{
+	my ($filename, $find, $replace, $blkno) = @_;
+
+	my $fh;
+	open($fh, '+<', $filename) or BAIL_OUT("open failed: $!");
+	binmode $fh;
+
+	my $offset = $blkno * $blksize;
+	my $buffer;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	sysread($fh, $buffer, $blksize) or BAIL_OUT("read failed: $!");
+
+	$buffer =~ s/$find/'"' . $replace . '"'/gee;
+
+	sysseek($fh, $offset, 0) or BAIL_OUT("seek failed: $!");
+	syswrite($fh, $buffer) or BAIL_OUT("write failed: $!");
+
+	close($fh) or BAIL_OUT("close failed: $!");
+
+	return;
+}
+
+done_testing();
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index b5f363562e3..26b98571b56 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -463,17 +463,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			Datum		parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
+			OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno,
 												   page, maxoff);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
+			OffsetNumber page_max_key_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory page_max_key_category;
 			Datum		page_max_key = gintuple_get_key(&state, idxtuple, &page_max_key_category);
 
 			if (rightlink != InvalidBlockNumber &&
-				ginCompareEntries(&state, attnum, page_max_key,
-								  page_max_key_category, parent_key,
-								  parent_key_category) > 0)
+				ginCompareAttEntries(&state, page_max_key_attnum, page_max_key,
+									 page_max_key_category, parent_key_attnum,
+									 parent_key, parent_key_category) < 0)
 			{
 				/* split page detected, install right link to the stack */
 				GinScanItem *ptr;
@@ -528,20 +529,18 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * First block is metadata, skip order check. Also, never check
-			 * for high key on rightmost page, as this key is not really
-			 * stored explicitly.
+			 * Never check for high key on rightmost inner page, as this key
+			 * is not really stored explicitly.
 			 *
 			 * Also make sure to not compare entries for different attnums,
 			 * which may be stored on the same page.
 			 */
-			if (i != FirstOffsetNumber && attnum == prev_attnum && stack->blkno != GIN_ROOT_BLKNO &&
-				!(i == maxoff && rightlink == InvalidBlockNumber))
+			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
-				if (ginCompareEntries(&state, attnum, prev_key,
-									  prev_key_category, current_key,
-									  current_key_category) >= 0)
+				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
+										 prev_key_category, attnum,
+										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
 							 errmsg("index \"%s\" has wrong tuple order on entry tree page, block %u, offset %u, rightlink %u",
@@ -556,13 +555,14 @@ gin_check_parent_keys_consistency(Relation rel,
 				i == maxoff)
 			{
 				GinNullCategory parent_key_category;
+				OffsetNumber parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 				Datum		parent_key = gintuple_get_key(&state,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareEntries(&state, attnum, current_key,
-									  current_key_category, parent_key,
-									  parent_key_category) > 0)
+				if (ginCompareAttEntries(&state, attnum, current_key,
+										 current_key_category, parent_key_attnum,
+										 parent_key, parent_key_category) > 0)
 				{
 					/*
 					 * There was a discrepancy between parent and child
@@ -581,6 +581,7 @@ gin_check_parent_keys_consistency(Relation rel,
 							 stack->blkno, stack->parentblk);
 					else
 					{
+						parent_key_attnum = gintuple_get_attrnum(&state, stack->parenttup);
 						parent_key = gintuple_get_key(&state,
 													  stack->parenttup,
 													  &parent_key_category);
@@ -589,9 +590,9 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareEntries(&state, attnum, current_key,
-											  current_key_category, parent_key,
-											  parent_key_category) > 0)
+						if (ginCompareAttEntries(&state, attnum, current_key,
+												 current_key_category, parent_key_attnum,
+												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
 									(errcode(ERRCODE_INDEX_CORRUPTED),
 									 errmsg("index \"%s\" has inconsistent records on page %u offset %u",
-- 
2.49.0

From d79cdc4ef65a23d8d42eb6f150373f6a76490c54 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@vondra.me>
Date: Mon, 16 Jun 2025 17:09:18 +0200
Subject: [PATCH v8 3/6] tweaks

---
 contrib/amcheck/verify_gin.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 26b98571b56..25d47eefcbc 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -514,9 +514,7 @@ gin_check_parent_keys_consistency(Relation rel,
 		{
 			ItemId		iid = PageGetItemIdCareful(rel, stack->blkno, page, i);
 			IndexTuple	idxtuple = (IndexTuple) PageGetItem(page, iid);
-			OffsetNumber attnum = gintuple_get_attrnum(&state, idxtuple);
-			GinNullCategory prev_key_category;
-			Datum		prev_key;
+			OffsetNumber current_attnum = gintuple_get_attrnum(&state, idxtuple);
 			GinNullCategory current_key_category;
 			Datum		current_key;
 
@@ -529,17 +527,23 @@ gin_check_parent_keys_consistency(Relation rel,
 			current_key = gintuple_get_key(&state, idxtuple, &current_key_category);
 
 			/*
-			 * Never check for high key on rightmost inner page, as this key
-			 * is not really stored explicitly.
+			 * Compare the entry to the preceding one.
 			 *
-			 * Also make sure to not compare entries for different attnums,
-			 * which may be stored on the same page.
+			 * Don't check for high key on the rightmost inner page, as this
+			 * key is not really stored explicitly.
+			 *
+			 * The entries may be for different attributes, so make sure to
+			 * use ginCompareAttEntries for comparison.
 			 */
-			if (i != FirstOffsetNumber && !(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
+			if ((i != FirstOffsetNumber) &&
+				!(i == maxoff && rightlink == InvalidBlockNumber && !GinPageIsLeaf(page)))
 			{
+				Datum		prev_key;
+				GinNullCategory prev_key_category;
+
 				prev_key = gintuple_get_key(&state, prev_tuple, &prev_key_category);
 				if (ginCompareAttEntries(&state, prev_attnum, prev_key,
-										 prev_key_category, attnum,
+										 prev_key_category, current_attnum,
 										 current_key, current_key_category) >= 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -560,7 +564,7 @@ gin_check_parent_keys_consistency(Relation rel,
 														  stack->parenttup,
 														  &parent_key_category);
 
-				if (ginCompareAttEntries(&state, attnum, current_key,
+				if (ginCompareAttEntries(&state, current_attnum, current_key,
 										 current_key_category, parent_key_attnum,
 										 parent_key, parent_key_category) > 0)
 				{
@@ -590,7 +594,7 @@ gin_check_parent_keys_consistency(Relation rel,
 						 * Check if it is properly adjusted. If succeed,
 						 * proceed to the next key.
 						 */
-						if (ginCompareAttEntries(&state, attnum, current_key,
+						if (ginCompareAttEntries(&state, current_attnum, current_key,
 												 current_key_category, parent_key_attnum,
 												 parent_key, parent_key_category) > 0)
 							ereport(ERROR,
@@ -645,7 +649,7 @@ gin_check_parent_keys_consistency(Relation rel,
 			}
 
 			prev_tuple = CopyIndexTuple(idxtuple);
-			prev_attnum = attnum;
+			prev_attnum = current_attnum;
 		}
 
 		LockBuffer(buffer, GIN_UNLOCK);
-- 
2.49.0

From 7326918e2ef50a52233c119712c7bc7abec993ba Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:39:13 +0300
Subject: [PATCH v8 4/6] amcheck: Fix parent key check in gin_index_check()

The checks introduced by commit 14ffaece0fb5 did not get the parent key
checks quite right, missing some data corruption cases. In particular:

* The "rightlink" check was not working as intended, because rightlink
  is a BlockNumber, and InvalidBlockNumber is 0xFFFFFFFF, so

    !GinPageGetOpaque(page)->rightlink

  almost always evaluates to false (except for rightlink=0). So in most
  cases parenttup was left NULL, preventing any checks against parent.

* Use GinGetDownlink() to retrieve child blkno to avoid triggering
  Assert, same as the core GIN code.

Issues reported by Arseniy Mikhin, along with a proposed patch. Review
by Andrey M. Borodin, cleanup and improvements by me.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/t/006_verify_gin.pl | 78 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        |  8 +--
 2 files changed, 82 insertions(+), 4 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index 7fdde170e06..308e53b2f75 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -34,6 +34,8 @@ $node->safe_psql(
 invalid_entry_order_leaf_page_test();
 invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
+inconsistent_with_parent_key__parent_key_corrupted_test();
+inconsistent_with_parent_key__child_key_corrupted_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -159,6 +161,82 @@ sub invalid_entry_columns_order_test
 	like($stderr, qr/$expected/);
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	# fill the table until we have a split
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string($filler_size) ||'}')::text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 1;  # root
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace it with something smaller then child's keys
+	string_replace_block(
+		$relpath,
+		'nnnnnnnnnn',
+		'aaaaaaaaaa',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has inconsistent records on page 3 offset 3";
+	like($stderr, qr/$expected/);
+}
+
+sub inconsistent_with_parent_key__child_key_corrupted_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	# fill the table until we have a split
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'llllllllll' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'mmmmmmmmmm' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'nnnnnnnnnn' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'xxxxxxxxxx' || random_string($filler_size) ||'}')::text[]);
+		INSERT INTO $relname (a) VALUES (('{' || 'yyyyyyyyyy' || random_string($filler_size) ||'}')::text[]);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	 ));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 3;  # leaf
+
+	# we have nnnnnnnnnn... as parent key in the root, so replace child key with something bigger
+	string_replace_block(
+		$relpath,
+		'nnnnnnnnnn',
+		'pppppppppp',
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\" has inconsistent records on page 3 offset 3";
+	like($stderr, qr/$expected/);
+}
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index 25d47eefcbc..ae36a4ea587 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -613,10 +613,10 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr = (GinScanItem *) palloc(sizeof(GinScanItem));
 				ptr->depth = stack->depth + 1;
 				/* last tuple in layer has no high key */
-				if (i != maxoff && !GinPageGetOpaque(page)->rightlink)
-					ptr->parenttup = CopyIndexTuple(idxtuple);
-				else
+				if (i == maxoff && rightlink == InvalidBlockNumber)
 					ptr->parenttup = NULL;
+				else
+					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
 				ptr->parentlsn = lsn;
@@ -754,7 +754,7 @@ gin_refind_parent(Relation rel, BlockNumber parentblkno,
 		ItemId		p_iid = PageGetItemIdCareful(rel, parentblkno, parentpage, o);
 		IndexTuple	itup = (IndexTuple) PageGetItem(parentpage, p_iid);
 
-		if (ItemPointerGetBlockNumber(&(itup->t_tid)) == childblkno)
+		if (GinGetDownlink(itup) == childblkno)
 		{
 			/* Found it! Make copy and return it */
 			result = CopyIndexTuple(itup);
-- 
2.49.0

From 65efe9243fcbabe0b8f28fcc743524060cadd730 Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:49:11 +0300
Subject: [PATCH v8 5/6] amcheck: Fix posting tree checks in gin_index_check()

Fix two issues in parent_key validation in posting trees:

* It's not enough to check stack->parentblk is valid to determine if the
  parentkey is valid. It's possible parentblk is set to a valid block
  number, but parentkey is invalid. So check parentkey directly.

* We don't need to invalidate parentkey for all child pages of the
  rightmost page. It's enough to invalidate it for the rightmost child
  only, which means we can check more cases (less false negatives).

Issues reported by Arseniy Mikhin, along with a proposed patch. Review
by Andrey M. Borodin, cleanup and improvements by me.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/t/006_verify_gin.pl | 39 +++++++++++++++++++++++++++++
 contrib/amcheck/verify_gin.c        | 12 +++------
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/contrib/amcheck/t/006_verify_gin.pl b/contrib/amcheck/t/006_verify_gin.pl
index 308e53b2f75..e540cd6606a 100644
--- a/contrib/amcheck/t/006_verify_gin.pl
+++ b/contrib/amcheck/t/006_verify_gin.pl
@@ -36,6 +36,7 @@ invalid_entry_order_inner_page_test();
 invalid_entry_columns_order_test();
 inconsistent_with_parent_key__parent_key_corrupted_test();
 inconsistent_with_parent_key__child_key_corrupted_test();
+inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test();
 
 sub invalid_entry_order_leaf_page_test
 {
@@ -237,6 +238,44 @@ sub inconsistent_with_parent_key__child_key_corrupted_test
 	like($stderr, qr/$expected/);
 }
 
+sub inconsistent_with_parent_key__parent_key_corrupted_posting_tree_test
+{
+	my $relname = "test";
+	my $indexname = "test_gin_idx";
+
+	$node->safe_psql(
+		'postgres', qq(
+		DROP TABLE IF EXISTS $relname;
+		CREATE TABLE $relname (a text[]);
+		INSERT INTO $relname (a) select ('{aaaaa}') from generate_series(1,10000);
+		CREATE INDEX $indexname ON $relname USING gin (a);
+	));
+	my $relpath = relation_filepath($indexname);
+
+	$node->stop;
+
+	my $blkno = 2;  # posting tree root
+
+	# we have a posting tree for 'aaaaa' key with the root at 2nd block
+	# and two leaf pages 3 and 4. replace 4th page's high key with (1,1)
+	# so that there are tid's in leaf page that are larger then the new high key.
+	my $find = pack('S*', 0, 4, 0) . '....';
+	my $replace = pack('S*', 0, 4, 0, 1, 1);
+	string_replace_block(
+		$relpath,
+		$find,
+		$replace,
+		$blkno
+	);
+
+	$node->start;
+
+	my ($result, $stdout, $stderr) = $node->psql('postgres', qq(SELECT gin_index_check('$indexname')));
+	my $expected = "index \"$indexname\": tid exceeds parent's high key in postingTree leaf on block 4";
+	like($stderr, qr/$expected/);
+}
+
+
 # Returns the filesystem path for the named relation.
 sub relation_filepath
 {
diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index ae36a4ea587..a1d57ac551f 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -346,7 +346,7 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				 * Check if this tuple is consistent with the downlink in the
 				 * parent.
 				 */
-				if (stack->parentblk != InvalidBlockNumber && i == maxoff &&
+				if (i == maxoff && ItemPointerIsValid(&stack->parentkey) &&
 					ItemPointerCompare(&stack->parentkey, &posting_item->key) < 0)
 					ereport(ERROR,
 							(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -359,14 +359,10 @@ gin_check_posting_tree_parent_keys_consistency(Relation rel, BlockNumber posting
 				ptr->depth = stack->depth + 1;
 
 				/*
-				 * Set rightmost parent key to invalid item pointer. Its value
-				 * is 'Infinity' and not explicitly stored.
+				 * The rightmost parent key is always invalid item pointer.
+				 * Its value is 'Infinity' and not explicitly stored.
 				 */
-				if (rightlink == InvalidBlockNumber)
-					ItemPointerSetInvalid(&ptr->parentkey);
-				else
-					ptr->parentkey = posting_item->key;
-
+				ptr->parentkey = posting_item->key;
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = BlockIdGetBlockNumber(&posting_item->child_blkno);
 				ptr->next = stack->next;
-- 
2.49.0

From ffc02618b19ff315f8daf992ad4a6d3d577adcca Mon Sep 17 00:00:00 2001
From: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Date: Mon, 9 Jun 2025 20:51:05 +0300
Subject: [PATCH v8 6/6] amcheck: Remove unused GinScanItem->parentlsn field

The field was introduced by commit 14ffaece0fb5, but is unused and
unnecessary. So remove it.

Issues reported by Arseniy Mikhin, along with a proposed patch. Review
by Andrey M. Borodin, cleanup and improvements by me.

Author: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com>
Reviewed-by: Andrey M. Borodin <x4mmm@yandex-team.ru>
Discussion: https://postgr.es/m/CAE7r3MJ611B9TE=YqBBncewp7-k64VWs+sjk7XF6fJUX77uFBA@mail.gmail.com
---
 contrib/amcheck/verify_gin.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/contrib/amcheck/verify_gin.c b/contrib/amcheck/verify_gin.c
index a1d57ac551f..c615d950736 100644
--- a/contrib/amcheck/verify_gin.c
+++ b/contrib/amcheck/verify_gin.c
@@ -38,7 +38,6 @@ typedef struct GinScanItem
 	int			depth;
 	IndexTuple	parenttup;
 	BlockNumber parentblk;
-	XLogRecPtr	parentlsn;
 	BlockNumber blkno;
 	struct GinScanItem *next;
 } GinScanItem;
@@ -417,7 +416,6 @@ gin_check_parent_keys_consistency(Relation rel,
 	stack->depth = 0;
 	stack->parenttup = NULL;
 	stack->parentblk = InvalidBlockNumber;
-	stack->parentlsn = InvalidXLogRecPtr;
 	stack->blkno = GIN_ROOT_BLKNO;
 
 	while (stack)
@@ -428,7 +426,6 @@ gin_check_parent_keys_consistency(Relation rel,
 		OffsetNumber i,
 					maxoff,
 					prev_attnum;
-		XLogRecPtr	lsn;
 		IndexTuple	prev_tuple;
 		BlockNumber rightlink;
 
@@ -438,7 +435,6 @@ gin_check_parent_keys_consistency(Relation rel,
 									RBM_NORMAL, strategy);
 		LockBuffer(buffer, GIN_SHARE);
 		page = (Page) BufferGetPage(buffer);
-		lsn = BufferGetLSNAtomic(buffer);
 		maxoff = PageGetMaxOffsetNumber(page);
 		rightlink = GinPageGetOpaque(page)->rightlink;
 
@@ -481,7 +477,6 @@ gin_check_parent_keys_consistency(Relation rel,
 				ptr->depth = stack->depth;
 				ptr->parenttup = CopyIndexTuple(stack->parenttup);
 				ptr->parentblk = stack->parentblk;
-				ptr->parentlsn = stack->parentlsn;
 				ptr->blkno = rightlink;
 				ptr->next = stack->next;
 				stack->next = ptr;
@@ -615,7 +610,6 @@ gin_check_parent_keys_consistency(Relation rel,
 					ptr->parenttup = CopyIndexTuple(idxtuple);
 				ptr->parentblk = stack->blkno;
 				ptr->blkno = GinGetDownlink(idxtuple);
-				ptr->parentlsn = lsn;
 				ptr->next = stack->next;
 				stack->next = ptr;
 			}
-- 
2.49.0