GIN pageinspect support for entry tree and posting tree

From be8abce940ea621f34a6b1949effad7d93bfa3c2 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v2] GIN pageinspect support for entry tree and posting tree
 non-leaf pages

---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  60 +++-
 contrib/pageinspect/ginfuncs.c                | 322 +++++++++++++++++-
 .../pageinspect/pageinspect--1.13--1.14.sql   |  28 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  19 +-
 6 files changed, 426 insertions(+), 7 deletions(-)
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..d108067c044 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -54,6 +95,21 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsuppoerted page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- rejrect fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index f6168d8e895..84de7a9f7d5 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,24 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
-
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +181,320 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid			indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation	indexRel;
+	OffsetNumber maxoff, offset;
+	TupleDesc	tupdesc;
+	bool		oneCol;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	maxoff = InvalidOffsetNumber;
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+	
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+	
+	
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page")));
+
+	/* Avoid bogus PageGetMaxOffsetNumber() call with deleted pages */
+	if (GinPageIsDeleted(page))
+		elog(NOTICE, "page is deleted");
+	else
+		maxoff = PageGetMaxOffsetNumber(page);
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		StringInfoData	buf;
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool	isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			Assert(!isnull);
+		}
+		else
+		{
+			TupleDesc tmpTupdesc;
+			Datum	res;
+			Form_pg_attribute attr;
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			Assert(!isnull);
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+ 			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+		}
+
+		initStringInfo(&buf);
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+			
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+	
+
+		values[3] = CStringGetTextDatum(buf.data);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	relation_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+	
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..71bc088ad12
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,28 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..0848ac41523 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -32,6 +38,15 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsuppoerted page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- rejrect fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
-- 
2.43.0

From bb80ecd61a830bc24b297d486a99d419ad77fc5c Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v3] GIN pageinspect support for entry tree and posting tree
 internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/ginfuncs.c                | 337 ++++++++++++++++++
 .../pageinspect/pageinspect--1.13--1.14.sql   |  28 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 6 files changed, 481 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..97057e37529 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..0fb98c0efd6 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,334 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea			*raw_page = PG_GETARG_BYTEA_P(0);
+	Oid				indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation		indexRel;
+	OffsetNumber	maxoff, offset;
+	TupleDesc		tupdesc;
+	bool			oneCol;
+	Page			page;
+	GinPageOpaque	opaq;
+	StringInfoData	buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	maxoff = InvalidOffsetNumber;
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a %s index",
+						RelationGetRelationName(indexRel), "GIN")));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN entry tree page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+	
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+	
+	
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page"),
+					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+					
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalud gin entry page tuple at offset %d", offset)));
+		}
+		else
+		{
+			TupleDesc			tmpTupdesc;
+			Datum				res;
+			Form_pg_attribute	attr;
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalud gin entry page tuple at offset %d", offset)));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+ 			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		initStringInfo(&buf);
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+			
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+	
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	relation_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+	
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..72f5e9bbea7
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,28 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..3e2738c71b0 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
-- 
2.43.0

From 8be472bd81fef7dc4fa6baa5872cee3b1e0036a7 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v4] GIN pageinspect support for entry tree and posting tree
 internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/ginfuncs.c                | 335 ++++++++++++++++++
 .../pageinspect/pageinspect--1.13--1.14.sql   |  28 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 6 files changed, 479 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..97057e37529 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..059db497e93 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,332 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea			*raw_page = PG_GETARG_BYTEA_P(0);
+	Oid				indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation		indexRel;
+	OffsetNumber	maxoff, offset;
+	TupleDesc		tupdesc;
+	bool			oneCol;
+	Page			page;
+	GinPageOpaque	opaq;
+	StringInfoData	buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a %s index",
+						RelationGetRelationName(indexRel), "GIN")));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN entry tree page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+	
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+	
+	
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page"),
+					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+					
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+		}
+		else
+		{
+			TupleDesc			tmpTupdesc;
+			Datum				res;
+			Form_pg_attribute	attr;
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+ 			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		initStringInfo(&buf);
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+			
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+	
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	relation_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+	
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..72f5e9bbea7
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,28 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..3e2738c71b0 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
-- 
2.43.0

From 947687725296941bbf3773e399bda93bf0da8148 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v5] GIN pageinspect support for entry tree and posting tree
 internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/ginfuncs.c                | 335 ++++++++++++++++++
 .../pageinspect/pageinspect--1.13--1.14.sql   |  28 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 7 files changed, 533 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..97057e37529 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..059db497e93 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,332 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea			*raw_page = PG_GETARG_BYTEA_P(0);
+	Oid				indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation		indexRel;
+	OffsetNumber	maxoff, offset;
+	TupleDesc		tupdesc;
+	bool			oneCol;
+	Page			page;
+	GinPageOpaque	opaq;
+	StringInfoData	buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a %s index",
+						RelationGetRelationName(indexRel), "GIN")));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN entry tree page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+	
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+	
+	
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page"),
+					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+					
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+		}
+		else
+		{
+			TupleDesc			tmpTupdesc;
+			Datum				res;
+			Form_pg_attribute	attr;
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+ 			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		initStringInfo(&buf);
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+			
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+	
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	relation_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+	
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..72f5e9bbea7
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,28 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..3e2738c71b0 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4c1c7162b54 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -718,6 +718,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+
+     <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+
+   </varlistentry>
   </variablelist>
  </sect2>
 
-- 
2.43.0

From 46d09ed2638257a3f4dab2636f4c5faca52153a5 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v6] GIN pageinspect support for entry tree and posting tree
 internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/ginfuncs.c                | 340 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  28 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 8 files changed, 539 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..97057e37529 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..aa5e8478fc0 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,337 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea			*raw_page = PG_GETARG_BYTEA_P(0);
+	Oid				indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation		indexRel;
+	OffsetNumber	maxoff, offset;
+	TupleDesc		tupdesc;
+	bool			oneCol;
+	Page			page;
+	GinPageOpaque	opaq;
+	StringInfoData	buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a %s index",
+						RelationGetRelationName(indexRel), "GIN")));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN entry tree page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+	
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+	
+	
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page"),
+					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+					
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+		}
+		else
+		{
+			TupleDesc			tmpTupdesc;
+			Datum				res;
+			Form_pg_attribute	attr;
+
+			/* Multi-column GIN indexes store 2-attribute tuple on each
+			* page item. First attribute is which heap attribute is stored
+			* as the second value in pair. To display value with proper output
+			* function we need to recreate tuple descriptor on each offset. */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+ 			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+			
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+	
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+	
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+		
+		
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..72f5e9bbea7
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,28 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..3e2738c71b0 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4c1c7162b54 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -718,6 +718,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+
+     <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+
+   </varlistentry>
   </variablelist>
  </sect2>
 
-- 
2.43.0

From 197d3a2e74b77c7c890f330b6ebc7056a6916279 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v7] GIN pageinspect support for entry tree and posting tree
 internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 338 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 687 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..97057e37529 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..eccc5707184
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is 
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..3cd5e4c0e65 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,335 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea			*raw_page = PG_GETARG_BYTEA_P(0);
+	Oid				indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation		indexRel;
+	OffsetNumber	maxoff, offset;
+	TupleDesc		tupdesc;
+	bool			oneCol;
+	Page			page;
+	GinPageOpaque	opaq;
+	StringInfoData	buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a %s index",
+						RelationGetRelationName(indexRel), "GIN")));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN entry tree page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page"),
+					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+		}
+		else
+		{
+			TupleDesc			tmpTupdesc;
+			Datum				res;
+			Form_pg_attribute	attr;
+
+			/* Multi-column GIN indexes store 2-attribute tuple on each
+			* page item. First attribute is which heap attribute is stored
+			* as the second value in pair. To display value with proper output
+			* function we need to recreate tuple descriptor on each offset. */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From dc870e8c17a1971267dd20f5bc92fc6b33abe137 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v8] GIN pageinspect support for entry tree and posting tree
 internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 338 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 687 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..702e9598594 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..52ddd2924ae
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..3cd5e4c0e65 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,335 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea			*raw_page = PG_GETARG_BYTEA_P(0);
+	Oid				indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation		indexRel;
+	OffsetNumber	maxoff, offset;
+	TupleDesc		tupdesc;
+	bool			oneCol;
+	Page			page;
+	GinPageOpaque	opaq;
+	StringInfoData	buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a %s index",
+						RelationGetRelationName(indexRel), "GIN")));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN entry tree page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for metapage")));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN entry tree page"),
+					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+	oneCol = tupdesc->natts == 1;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber	indAtt;
+		Datum		values[4];
+		bool		nulls[4];
+		int			ndecoded, i;
+		Datum	   *tids_datum;
+		ItemPointer items_orig;
+		bool		free_items_orig;
+		Datum		attrVal;
+		Oid			foutoid;
+		bool		typisvarlena;
+		Oid			typoid;
+		char*		value;
+		bool		nq;
+		char*		tmp;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (oneCol)
+		{
+			indAtt = FirstOffsetNumber;
+			/* here we can safely reuse pg_class's tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+							&isnull);
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+		}
+		else
+		{
+			TupleDesc			tmpTupdesc;
+			Datum				res;
+			Form_pg_attribute	attr;
+
+			/* Multi-column GIN indexes store 2-attribute tuple on each
+			* page item. First attribute is which heap attribute is stored
+			* as the second value in pair. To display value with proper output
+			* function we need to recreate tuple descriptor on each offset. */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
+								&isnull);
+
+			/* we do not expect null for first attr in multi-column GIN */
+			if (isnull)
+				ereport(ERROR,
+						(errcode(ERRCODE_INDEX_CORRUPTED),
+							errmsg("invalid gin entry page tuple at offset %d", offset)));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+					tmpTupdesc,
+					&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+			for (i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff, offset;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("gin_datapage_items is unsupported for GIN fast update list")));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a GIN data tree page")));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is a GIN data leaf tree page")));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem* item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From b424062035a43c894cf6d11b854a917be0cad6d8 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 7 Jan 2026 17:37:05 +0100
Subject: [PATCH] some code cleanup

---
 contrib/pageinspect/ginfuncs.c | 95 ++++++++++++++++------------------
 1 file changed, 44 insertions(+), 51 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index 3cd5e4c0e65..4294b640a9a 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -191,17 +191,16 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 	Oid				indexRelid = PG_GETARG_OID(1);
 	ReturnSetInfo	*rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
 	Relation		indexRel;
-	OffsetNumber	maxoff, offset;
+	OffsetNumber	maxoff;
 	TupleDesc		tupdesc;
-	bool			oneCol;
 	Page			page;
 	GinPageOpaque	opaq;
 	StringInfoData	buf;
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	InitMaterializedSRF(fcinfo, 0);
 
@@ -210,9 +209,9 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 
 	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
 		ereport(ERROR,
-				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
-				 errmsg("\"%s\" is not a %s index",
-						RelationGetRelationName(indexRel), "GIN")));
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a %s index",
+					   RelationGetRelationName(indexRel), "GIN"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -224,58 +223,46 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					errmsg("input page is not a valid GIN entry tree page"),
-					errdetail("Expected special size %d, got %d.",
-							(int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							(int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN entry tree page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
-
 	/* we only support entry tree in this function, check that */
 	if (opaq->flags & GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					errmsg("gin_entrypage_items is unsupported for metapage")));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items is unsupported for metapage"));
 
 
 	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					errmsg("gin_entrypage_items is unsupported for fast list pages")));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items is unsupported for fast list pages"));
 
 
 	if (opaq->flags & GIN_DATA)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					errmsg("input page is not a GIN entry tree page"),
-					errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items")));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN entry tree page"),
+				errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
 
 	initStringInfo(&buf);
 	maxoff = PageGetMaxOffsetNumber(page);
 
 	tupdesc = RelationGetDescr(indexRel);
-	oneCol = tupdesc->natts == 1;
 
-	for (offset = FirstOffsetNumber;
+	for (OffsetNumber offset = FirstOffsetNumber;
 		 offset <= maxoff;
 		 offset = OffsetNumberNext(offset))
 	{
 		OffsetNumber	indAtt;
 		Datum		values[4];
-		bool		nulls[4];
-		int			ndecoded, i;
-		Datum	   *tids_datum;
-		ItemPointer items_orig;
-		bool		free_items_orig;
+		bool		nulls[4] = {0};
 		Datum		attrVal;
-		Oid			foutoid;
-		bool		typisvarlena;
-		Oid			typoid;
-		char*		value;
-		bool		nq;
-		char*		tmp;
 		bool		isnull;
 		IndexTuple	idxtuple;
 		ItemId		iid = PageGetItemId(page, offset);
@@ -285,20 +272,17 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 
 		idxtuple = (IndexTuple) PageGetItem(page, iid);
 
-		memset(nulls, 0, sizeof(nulls));
-
 		values[0] = UInt16GetDatum(offset);
 
-		if (oneCol)
+		if (tupdesc->natts == 1)
 		{
 			indAtt = FirstOffsetNumber;
 			/* here we can safely reuse pg_class's tuple descriptor. */
-			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
-							&isnull);
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
 			if (isnull)
 				ereport(ERROR,
-						(errcode(ERRCODE_INDEX_CORRUPTED),
-							errmsg("invalid gin entry page tuple at offset %d", offset)));
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %d", offset));
 		}
 		else
 		{
@@ -313,14 +297,13 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 
 			/* orig tuple reuse is safe */
 
-			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc,
-								&isnull);
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
 
 			/* we do not expect null for first attr in multi-column GIN */
 			if (isnull)
 				ereport(ERROR,
-						(errcode(ERRCODE_INDEX_CORRUPTED),
-							errmsg("invalid gin entry page tuple at offset %d", offset)));
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %d", offset));
 
 			indAtt = DatumGetUInt16(res);
 
@@ -346,16 +329,22 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 
 		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
 
-		if (!isnull) {
+		if (!isnull)
+		{
+			Oid			foutoid;
+			bool		typisvarlena;
+			Oid			typoid;
+			char*		value;
+			bool		nq;
+
 			/* Most of this is copied from record_out(). */
 			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
 			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
 			value = OidOutputFunctionCall(foutoid, attrVal);
 
-
 			/* Check whether we need double quotes for this value */
 			nq = (value[0] == '\0');	/* force quotes for empty string */
-			for (tmp = value; *tmp; tmp++)
+			for (const char *tmp = value; *tmp; tmp++)
 			{
 				char		ch = *tmp;
 
@@ -371,7 +360,7 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 			/* And emit the string */
 			if (nq)
 				appendStringInfoCharMacro(&buf, '"');
-			for (tmp = value; *tmp; tmp++)
+			for (const char *tmp = value; *tmp; tmp++)
 			{
 				char		ch = *tmp;
 
@@ -387,7 +376,6 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 			appendStringInfo(&buf, "NULL");
 		}
 
-
 		values[3] = CStringGetTextDatum(buf.data);
 		resetStringInfo(&buf);
 
@@ -398,6 +386,11 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 		}
 		else
 		{
+			int			ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool		free_items_orig;
+
 			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
 			/* Get list of item pointers from the tuple. */
 			if (GinItupIsCompressed(idxtuple))
@@ -412,8 +405,8 @@ gin_entrypage_items(PG_FUNCTION_ARGS)
 				free_items_orig = false;
 			}
 
-			tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
-			for (i = 0; i < ndecoded; i++)
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
 				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
 			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
 
-- 
2.52.0

From c34fc7c81214f16530881e9679c0a6281681c243 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v9 2/2] GIN pageinspect support for entry tree and posting
 tree internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru

some code cleanup
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 328 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 677 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..702e9598594 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..b9257e1840a
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (41,125)
+-[ RECORD 2 ]--------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 136
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ccd2a0582a1..e0621cd2c26 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS) {
@@ -171,6 +180,325 @@ typedef struct gin_leafpage_items_state {
 	GinPostingList *lastseg;
 }	    gin_leafpage_items_state;
 
+/*
+ * gin_entrypage_items
+ *
+ * Allows inspection of contents of an entry tree page.
+ */
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS) {
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid	    indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation    indexRel;
+	OffsetNumber maxoff;
+	TupleDesc   tupdesc;
+	Page	    page;
+	GinPageOpaque opaq;
+	StringInfoData buf;
+
+	if (!superuser())
+		ereport(ERROR,
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+			errcode(ERRCODE_WRONG_OBJECT_TYPE),
+			errmsg("\"%s\" is not a %s index",
+				RelationGetRelationName(indexRel), "GIN"));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page)) {
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a valid GIN entry tree page"),
+			errdetail("Expected special size %d, got %d.",
+				(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+				PageGetSpecialSize(page)));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("gin_entrypage_items is unsupported for metapage"));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("gin_entrypage_items is unsupported for fast list pages"));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a GIN entry tree page"),
+			errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		offset <= maxoff;
+		offset = OffsetNumberNext(offset)) {
+		OffsetNumber indAtt;
+		Datum	    values[4];
+		bool	    nulls[4] = {0};
+		Datum	    attrVal;
+		bool	    isnull;
+		IndexTuple  idxtuple;
+		ItemId	    iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (tupdesc->natts == 1) {
+			indAtt = FirstOffsetNumber;
+			/*
+			 * here we can safely reuse pg_class's tuple
+			 * descriptor.
+			 */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+			if (isnull)
+				ereport(ERROR,
+					errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("invalid gin entry page tuple at offset %d", offset));
+		} else {
+			TupleDesc   tmpTupdesc;
+			Datum	    res;
+			Form_pg_attribute attr;
+
+			/*
+			 * Multi-column GIN indexes store 2-attribute tuple on
+			 * each page item. First attribute is which heap
+			 * attribute is stored as the second value in pair. To
+			 * display value with proper output function we need
+			 * to recreate tuple descriptor on each offset.
+			 */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+
+			/*
+			 * we do not expect null for first attr in
+			 * multi-column GIN
+			 */
+			if (isnull)
+				ereport(ERROR,
+					errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("invalid gin entry page tuple at offset %d", offset));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+				INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+				attr->atttypid,
+				attr->atttypmod,
+				attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+				attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+				tmpTupdesc,
+				&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			Oid	    foutoid;
+			bool	    typisvarlena;
+			Oid	    typoid;
+			char	   *value;
+			bool	    nq;
+
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for
+							 * empty string */
+			for (const char *tmp = value; *tmp; tmp++) {
+				char	    ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch)) {
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (const char *tmp = value; *tmp; tmp++) {
+				char	    ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		} else {
+			appendStringInfo(&buf, "NULL");
+		}
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple)) {
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		} else {
+			int	    ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool	    free_items_orig;
+
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple)) {
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			} else {
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+/*
+ * gin_datapage_items
+ *
+ * Allows inspection of contents of an posting tree non-leaf page.
+ */
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS) {
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff;
+	Page	    page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page)) {
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+					(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+					(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("gin_datapage_items is unsupported for GIN fast update list"));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a GIN data tree page"));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is a GIN data leaf tree page"),
+			errhint("This appears to be a GIN posting leaf tree page. Please use gin_leafpage_items."));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		offset <= maxoff;
+		offset = OffsetNumberNext(offset)) {
+		Datum	    values[3];
+		bool	    nulls[3];
+		PostingItem *item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From 41f52c04780435aa51bc6e90e959fb75105e9764 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Wed, 7 Jan 2026 19:38:52 +0000
Subject: [PATCH v9 1/2] Prelimitary cleaunup

This patch fixes whitespace/tab issue enforcing single style
across existing ginfuncs.c code. This patch also switches
palloc to our newly-preferred palloc_array.

Per Peter Eisentraut's patch in thread.

Discussion: https://www.postgresql.org/message-id/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E%3Dg%3Dg6aZANyE_OoQ%40mail.gmail.com
---
 contrib/pageinspect/ginfuncs.c | 135 +++++++++++++++------------------
 1 file changed, 63 insertions(+), 72 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..ccd2a0582a1 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -25,21 +25,20 @@ PG_FUNCTION_INFO_V1(gin_leafpage_items);
 
 
 Datum
-gin_metapage_info(PG_FUNCTION_ARGS)
-{
+gin_metapage_info(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
-	TupleDesc	tupdesc;
-	Page		page;
+	TupleDesc   tupdesc;
+	Page	    page;
 	GinPageOpaque opaq;
 	GinMetaPageData *metadata;
-	HeapTuple	resultTuple;
-	Datum		values[10];
-	bool		nulls[10];
+	HeapTuple   resultTuple;
+	Datum	    values[10];
+	bool	    nulls[10];
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -48,20 +47,20 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN metapage"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a valid GIN metapage"),
+			errdetail("Expected special size %d, got %d.",
+				(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+				(int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
 	if (opaq->flags != GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a GIN metapage"),
-				 errdetail("Flags %04X, expected %04X",
-						   opaq->flags, GIN_META)));
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a GIN metapage"),
+			errdetail("Flags %04X, expected %04X",
+				opaq->flags, GIN_META));
 
 	/* Build a tuple descriptor for our result type */
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
@@ -93,23 +92,22 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 
 Datum
-gin_page_opaque_info(PG_FUNCTION_ARGS)
-{
+gin_page_opaque_info(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
-	TupleDesc	tupdesc;
-	Page		page;
+	TupleDesc   tupdesc;
+	Page	    page;
 	GinPageOpaque opaq;
-	HeapTuple	resultTuple;
-	Datum		values[3];
-	bool		nulls[3];
-	Datum		flags[16];
-	int			nflags = 0;
-	uint16		flagbits;
+	HeapTuple   resultTuple;
+	Datum	    values[3];
+	bool	    nulls[3];
+	Datum	    flags[16];
+	int	    nflags = 0;
+	uint16	    flagbits;
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+			(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions")));
 
 	page = get_page_from_raw(raw_page);
 
@@ -118,11 +116,11 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN data leaf page"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a valid GIN data leaf page"),
+			errdetail("Expected special size %d, got %d.",
+				(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+				(int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
@@ -149,9 +147,8 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 	if (flagbits & GIN_COMPRESSED)
 		flags[nflags++] = CStringGetTextDatum("compressed");
 	flagbits &= ~(GIN_DATA | GIN_LEAF | GIN_DELETED | GIN_META | GIN_LIST |
-				  GIN_LIST_FULLROW | GIN_INCOMPLETE_SPLIT | GIN_COMPRESSED);
-	if (flagbits)
-	{
+		GIN_LIST_FULLROW | GIN_INCOMPLETE_SPLIT | GIN_COMPRESSED);
+	if (flagbits) {
 		/* any flags we don't recognize are printed in hex */
 		flags[nflags++] = DirectFunctionCall1(to_hex32, Int32GetDatum(flagbits));
 	}
@@ -168,30 +165,27 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 	return HeapTupleGetDatum(resultTuple);
 }
 
-typedef struct gin_leafpage_items_state
-{
-	TupleDesc	tupd;
+typedef struct gin_leafpage_items_state {
+	TupleDesc   tupd;
 	GinPostingList *seg;
 	GinPostingList *lastseg;
-} gin_leafpage_items_state;
+}	    gin_leafpage_items_state;
 
 Datum
-gin_leafpage_items(PG_FUNCTION_ARGS)
-{
+gin_leafpage_items(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
 	FuncCallContext *fctx;
 	gin_leafpage_items_state *inter_call_data;
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
 
-	if (SRF_IS_FIRSTCALL())
-	{
-		TupleDesc	tupdesc;
+	if (SRF_IS_FIRSTCALL()) {
+		TupleDesc   tupdesc;
 		MemoryContext mctx;
-		Page		page;
+		Page	    page;
 		GinPageOpaque opaq;
 
 		fctx = SRF_FIRSTCALL_INIT();
@@ -199,28 +193,27 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		page = get_page_from_raw(raw_page);
 
-		if (PageIsNew(page))
-		{
+		if (PageIsNew(page)) {
 			MemoryContextSwitchTo(mctx);
 			PG_RETURN_NULL();
 		}
 
 		if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a valid GIN data leaf page"),
-					 errdetail("Expected special size %d, got %d.",
-							   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+					(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+					(int) PageGetSpecialSize(page)));
 
 		opaq = GinPageGetOpaque(page);
 		if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a compressed GIN data leaf page"),
-					 errdetail("Flags %04X, expected %04X",
-							   opaq->flags,
-							   (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a compressed GIN data leaf page"),
+				errdetail("Flags %04X, expected %04X",
+					opaq->flags,
+					(GIN_DATA | GIN_LEAF | GIN_COMPRESSED)));
 
 		inter_call_data = palloc_object(gin_leafpage_items_state);
 
@@ -233,7 +226,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 		inter_call_data->seg = GinDataLeafPageGetPostingList(page);
 		inter_call_data->lastseg = (GinPostingList *)
 			(((char *) inter_call_data->seg) +
-			 GinDataLeafPageGetPostingListSize(page));
+			GinDataLeafPageGetPostingListSize(page));
 
 		fctx->user_fctx = inter_call_data;
 
@@ -243,15 +236,13 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 	fctx = SRF_PERCALL_SETUP();
 	inter_call_data = fctx->user_fctx;
 
-	if (inter_call_data->seg != inter_call_data->lastseg)
-	{
+	if (inter_call_data->seg != inter_call_data->lastseg) {
 		GinPostingList *cur = inter_call_data->seg;
-		HeapTuple	resultTuple;
-		Datum		result;
-		Datum		values[3];
-		bool		nulls[3];
-		int			ndecoded,
-					i;
+		HeapTuple   resultTuple;
+		Datum	    result;
+		Datum	    values[3];
+		bool	    nulls[3];
+		int	    ndecoded, i;
 		ItemPointer tids;
 		Datum	   *tids_datum;
 
@@ -262,7 +253,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		/* build an array of decoded item pointers */
 		tids = ginPostingListDecode(cur, &ndecoded);
-		tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+		tids_datum = palloc_array(Datum, ndecoded);
 		for (i = 0; i < ndecoded; i++)
 			tids_datum[i] = ItemPointerGetDatum(&tids[i]);
 		values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
-- 
2.43.0

From 41f52c04780435aa51bc6e90e959fb75105e9764 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Wed, 7 Jan 2026 19:38:52 +0000
Subject: [PATCH v10 1/2] Prelimitary cleaunup

This patch fixes whitespace/tab issue enforcing single style
across existing ginfuncs.c code. This patch also switches
palloc to our newly-preferred palloc_array.

Per Peter Eisentraut's patch in thread.

Discussion: https://www.postgresql.org/message-id/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E%3Dg%3Dg6aZANyE_OoQ%40mail.gmail.com
---
 contrib/pageinspect/ginfuncs.c | 135 +++++++++++++++------------------
 1 file changed, 63 insertions(+), 72 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..ccd2a0582a1 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -25,21 +25,20 @@ PG_FUNCTION_INFO_V1(gin_leafpage_items);
 
 
 Datum
-gin_metapage_info(PG_FUNCTION_ARGS)
-{
+gin_metapage_info(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
-	TupleDesc	tupdesc;
-	Page		page;
+	TupleDesc   tupdesc;
+	Page	    page;
 	GinPageOpaque opaq;
 	GinMetaPageData *metadata;
-	HeapTuple	resultTuple;
-	Datum		values[10];
-	bool		nulls[10];
+	HeapTuple   resultTuple;
+	Datum	    values[10];
+	bool	    nulls[10];
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -48,20 +47,20 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN metapage"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a valid GIN metapage"),
+			errdetail("Expected special size %d, got %d.",
+				(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+				(int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
 	if (opaq->flags != GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a GIN metapage"),
-				 errdetail("Flags %04X, expected %04X",
-						   opaq->flags, GIN_META)));
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a GIN metapage"),
+			errdetail("Flags %04X, expected %04X",
+				opaq->flags, GIN_META));
 
 	/* Build a tuple descriptor for our result type */
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
@@ -93,23 +92,22 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 
 Datum
-gin_page_opaque_info(PG_FUNCTION_ARGS)
-{
+gin_page_opaque_info(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
-	TupleDesc	tupdesc;
-	Page		page;
+	TupleDesc   tupdesc;
+	Page	    page;
 	GinPageOpaque opaq;
-	HeapTuple	resultTuple;
-	Datum		values[3];
-	bool		nulls[3];
-	Datum		flags[16];
-	int			nflags = 0;
-	uint16		flagbits;
+	HeapTuple   resultTuple;
+	Datum	    values[3];
+	bool	    nulls[3];
+	Datum	    flags[16];
+	int	    nflags = 0;
+	uint16	    flagbits;
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+			(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions")));
 
 	page = get_page_from_raw(raw_page);
 
@@ -118,11 +116,11 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN data leaf page"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a valid GIN data leaf page"),
+			errdetail("Expected special size %d, got %d.",
+				(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+				(int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
@@ -149,9 +147,8 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 	if (flagbits & GIN_COMPRESSED)
 		flags[nflags++] = CStringGetTextDatum("compressed");
 	flagbits &= ~(GIN_DATA | GIN_LEAF | GIN_DELETED | GIN_META | GIN_LIST |
-				  GIN_LIST_FULLROW | GIN_INCOMPLETE_SPLIT | GIN_COMPRESSED);
-	if (flagbits)
-	{
+		GIN_LIST_FULLROW | GIN_INCOMPLETE_SPLIT | GIN_COMPRESSED);
+	if (flagbits) {
 		/* any flags we don't recognize are printed in hex */
 		flags[nflags++] = DirectFunctionCall1(to_hex32, Int32GetDatum(flagbits));
 	}
@@ -168,30 +165,27 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 	return HeapTupleGetDatum(resultTuple);
 }
 
-typedef struct gin_leafpage_items_state
-{
-	TupleDesc	tupd;
+typedef struct gin_leafpage_items_state {
+	TupleDesc   tupd;
 	GinPostingList *seg;
 	GinPostingList *lastseg;
-} gin_leafpage_items_state;
+}	    gin_leafpage_items_state;
 
 Datum
-gin_leafpage_items(PG_FUNCTION_ARGS)
-{
+gin_leafpage_items(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
 	FuncCallContext *fctx;
 	gin_leafpage_items_state *inter_call_data;
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
 
-	if (SRF_IS_FIRSTCALL())
-	{
-		TupleDesc	tupdesc;
+	if (SRF_IS_FIRSTCALL()) {
+		TupleDesc   tupdesc;
 		MemoryContext mctx;
-		Page		page;
+		Page	    page;
 		GinPageOpaque opaq;
 
 		fctx = SRF_FIRSTCALL_INIT();
@@ -199,28 +193,27 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		page = get_page_from_raw(raw_page);
 
-		if (PageIsNew(page))
-		{
+		if (PageIsNew(page)) {
 			MemoryContextSwitchTo(mctx);
 			PG_RETURN_NULL();
 		}
 
 		if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a valid GIN data leaf page"),
-					 errdetail("Expected special size %d, got %d.",
-							   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+					(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+					(int) PageGetSpecialSize(page)));
 
 		opaq = GinPageGetOpaque(page);
 		if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a compressed GIN data leaf page"),
-					 errdetail("Flags %04X, expected %04X",
-							   opaq->flags,
-							   (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a compressed GIN data leaf page"),
+				errdetail("Flags %04X, expected %04X",
+					opaq->flags,
+					(GIN_DATA | GIN_LEAF | GIN_COMPRESSED)));
 
 		inter_call_data = palloc_object(gin_leafpage_items_state);
 
@@ -233,7 +226,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 		inter_call_data->seg = GinDataLeafPageGetPostingList(page);
 		inter_call_data->lastseg = (GinPostingList *)
 			(((char *) inter_call_data->seg) +
-			 GinDataLeafPageGetPostingListSize(page));
+			GinDataLeafPageGetPostingListSize(page));
 
 		fctx->user_fctx = inter_call_data;
 
@@ -243,15 +236,13 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 	fctx = SRF_PERCALL_SETUP();
 	inter_call_data = fctx->user_fctx;
 
-	if (inter_call_data->seg != inter_call_data->lastseg)
-	{
+	if (inter_call_data->seg != inter_call_data->lastseg) {
 		GinPostingList *cur = inter_call_data->seg;
-		HeapTuple	resultTuple;
-		Datum		result;
-		Datum		values[3];
-		bool		nulls[3];
-		int			ndecoded,
-					i;
+		HeapTuple   resultTuple;
+		Datum	    result;
+		Datum	    values[3];
+		bool	    nulls[3];
+		int	    ndecoded, i;
 		ItemPointer tids;
 		Datum	   *tids_datum;
 
@@ -262,7 +253,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		/* build an array of decoded item pointers */
 		tids = ginPostingListDecode(cur, &ndecoded);
-		tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+		tids_datum = palloc_array(Datum, ndecoded);
 		for (i = 0; i < ndecoded; i++)
 			tids_datum[i] = ItemPointerGetDatum(&tids[i]);
 		values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
-- 
2.43.0

From f1b3a3ecfd9731ead65e515d5ea14516b7010c6f Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v10 2/2] GIN pageinspect support for entry tree and posting
 tree internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru

some code cleanup
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 328 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 677 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..dee2894c2ac 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..1d504cb5557
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (41,125)
+-[ RECORD 2 ]--------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 136
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ccd2a0582a1..e0621cd2c26 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS) {
@@ -171,6 +180,325 @@ typedef struct gin_leafpage_items_state {
 	GinPostingList *lastseg;
 }	    gin_leafpage_items_state;
 
+/*
+ * gin_entrypage_items
+ *
+ * Allows inspection of contents of an entry tree page.
+ */
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS) {
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid	    indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation    indexRel;
+	OffsetNumber maxoff;
+	TupleDesc   tupdesc;
+	Page	    page;
+	GinPageOpaque opaq;
+	StringInfoData buf;
+
+	if (!superuser())
+		ereport(ERROR,
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+			errcode(ERRCODE_WRONG_OBJECT_TYPE),
+			errmsg("\"%s\" is not a %s index",
+				RelationGetRelationName(indexRel), "GIN"));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page)) {
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a valid GIN entry tree page"),
+			errdetail("Expected special size %d, got %d.",
+				(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+				PageGetSpecialSize(page)));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("gin_entrypage_items is unsupported for metapage"));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("gin_entrypage_items is unsupported for fast list pages"));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a GIN entry tree page"),
+			errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		offset <= maxoff;
+		offset = OffsetNumberNext(offset)) {
+		OffsetNumber indAtt;
+		Datum	    values[4];
+		bool	    nulls[4] = {0};
+		Datum	    attrVal;
+		bool	    isnull;
+		IndexTuple  idxtuple;
+		ItemId	    iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (tupdesc->natts == 1) {
+			indAtt = FirstOffsetNumber;
+			/*
+			 * here we can safely reuse pg_class's tuple
+			 * descriptor.
+			 */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+			if (isnull)
+				ereport(ERROR,
+					errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("invalid gin entry page tuple at offset %d", offset));
+		} else {
+			TupleDesc   tmpTupdesc;
+			Datum	    res;
+			Form_pg_attribute attr;
+
+			/*
+			 * Multi-column GIN indexes store 2-attribute tuple on
+			 * each page item. First attribute is which heap
+			 * attribute is stored as the second value in pair. To
+			 * display value with proper output function we need
+			 * to recreate tuple descriptor on each offset.
+			 */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+
+			/*
+			 * we do not expect null for first attr in
+			 * multi-column GIN
+			 */
+			if (isnull)
+				ereport(ERROR,
+					errcode(ERRCODE_INDEX_CORRUPTED),
+					errmsg("invalid gin entry page tuple at offset %d", offset));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+				INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+				attr->atttypid,
+				attr->atttypmod,
+				attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+				attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+				tmpTupdesc,
+				&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull) {
+			Oid	    foutoid;
+			bool	    typisvarlena;
+			Oid	    typoid;
+			char	   *value;
+			bool	    nq;
+
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for
+							 * empty string */
+			for (const char *tmp = value; *tmp; tmp++) {
+				char	    ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch)) {
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (const char *tmp = value; *tmp; tmp++) {
+				char	    ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		} else {
+			appendStringInfo(&buf, "NULL");
+		}
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple)) {
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		} else {
+			int	    ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool	    free_items_orig;
+
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple)) {
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			} else {
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+/*
+ * gin_datapage_items
+ *
+ * Allows inspection of contents of an posting tree non-leaf page.
+ */
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS) {
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff;
+	Page	    page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+			errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+			errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page)) {
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+					(int) MAXALIGN(sizeof(GinPageOpaqueData)),
+					(int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("gin_datapage_items is unsupported for GIN fast update list"));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is not a GIN data tree page"));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+			errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+			errmsg("input page is a GIN data leaf tree page"),
+			errhint("This appears to be a GIN posting leaf tree page. Please use gin_leafpage_items."));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		offset <= maxoff;
+		offset = OffsetNumberNext(offset)) {
+		Datum	    values[3];
+		bool	    nulls[3];
+		PostingItem *item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS) {
 	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From 5c621d40155f9969ec7569293f91dc82c10cb324 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v11 2/2] GIN pageinspect support for entry tree and posting
 tree internal pages

This patch provides new version for pageinspect contrib module including
two new functions:

* gin_entrypage_items.
* gin_datapage_items.

These two functions can be used to examine GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used of both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine non-leaf posting tree
pages.

We keep the different functions here mainly because of different GIN
pages layoff.

Note that fast-list pages are out of scope of this patch.

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru
Reviewed-by: Roman Khapov rkhapov@yandex-team.ru

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 346 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 695 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..dee2894c2ac 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..e37df702afd
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]--------
+itemoffset | 1
+downlink   | 4
+item_tid   | (41,125)
+-[ RECORD 2 ]--------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for metapage
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  input page is not a GIN entry tree page
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 136
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items is unsupported for fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index b7bd7a3f4cd..c825027781d 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,343 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+/*
+ * gin_entrypage_items
+ *
+ * Allows inspection of contents of an entry tree page.
+ */
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid			indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation	indexRel;
+	OffsetNumber maxoff;
+	TupleDesc	tupdesc;
+	Page		page;
+	GinPageOpaque opaq;
+	StringInfoData buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a %s index",
+					   RelationGetRelationName(indexRel), "GIN"));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN entry tree page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  PageGetSpecialSize(page)));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items is unsupported for metapage"));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items is unsupported for fast list pages"));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN entry tree page"),
+				errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber indAtt;
+		Datum		values[4];
+		bool		nulls[4] = {0};
+		Datum		attrVal;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			elog(ERROR, "invalid ItemId");
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (tupdesc->natts == 1)
+		{
+			indAtt = FirstOffsetNumber;
+
+			/*
+			 * here we can safely reuse pg_class's tuple descriptor.
+			 */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %d", offset));
+		}
+		else
+		{
+			TupleDesc	tmpTupdesc;
+			Datum		res;
+			Form_pg_attribute attr;
+
+			/*
+			 * Multi-column GIN indexes store 2-attribute tuple on each page
+			 * item. First attribute is which heap attribute is stored as the
+			 * second value in pair. To display value with proper output
+			 * function we need to recreate tuple descriptor on each offset.
+			 */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+
+			/*
+			 * we do not expect null for first attr in multi-column GIN
+			 */
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %d", offset));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+									tmpTupdesc,
+									&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull)
+		{
+			Oid			foutoid;
+			bool		typisvarlena;
+			Oid			typoid;
+			char	   *value;
+			bool		nq;
+
+			/* Most of this is copied from record_out(). */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			int			ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool		free_items_orig;
+
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+/*
+ * gin_datapage_items
+ *
+ * Allows inspection of contents of an posting tree non-leaf page.
+ */
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("input page is not a valid GIN data leaf page"),
+				 errdetail("Expected special size %d, got %d.",
+						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						   (int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support posting tree non-leaf in this function, check that */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_datapage_items is unsupported for GIN fast update list"));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN data tree page"));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is a GIN data leaf tree page"),
+				errhint("This appears to be a GIN posting leaf tree page. Please use gin_leafpage_items."));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem *item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From c33be44852aa4286e0c85ffd3457caf7b283866a Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Wed, 7 Jan 2026 19:38:52 +0000
Subject: [PATCH v11 1/2] Preliminary cleanup

This patch fixes whitespace/tab issues enforcing single style
across existing ginfuncs.c code. This patch also switches
palloc to our newly-preferred palloc_array.

Per Peter Eisentraut's patch in thread.

Reviewed-by: Andrey Borodin x4mmm@yandex-team.ru

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/ginfuncs.c | 58 +++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..b7bd7a3f4cd 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -38,8 +38,8 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -48,20 +48,20 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN metapage"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN metapage"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
 	if (opaq->flags != GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a GIN metapage"),
-				 errdetail("Flags %04X, expected %04X",
-						   opaq->flags, GIN_META)));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN metapage"),
+				errdetail("Flags %04X, expected %04X",
+						  opaq->flags, GIN_META));
 
 	/* Build a tuple descriptor for our result type */
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
@@ -118,11 +118,11 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN data leaf page"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
@@ -184,8 +184,8 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	if (SRF_IS_FIRSTCALL())
 	{
@@ -207,20 +207,20 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a valid GIN data leaf page"),
-					 errdetail("Expected special size %d, got %d.",
-							   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							   (int) PageGetSpecialSize(page))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							  (int) PageGetSpecialSize(page)));
 
 		opaq = GinPageGetOpaque(page);
 		if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a compressed GIN data leaf page"),
-					 errdetail("Flags %04X, expected %04X",
-							   opaq->flags,
-							   (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a compressed GIN data leaf page"),
+					errdetail("Flags %04X, expected %04X",
+							  opaq->flags,
+							  (GIN_DATA | GIN_LEAF | GIN_COMPRESSED)));
 
 		inter_call_data = palloc_object(gin_leafpage_items_state);
 
@@ -262,7 +262,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		/* build an array of decoded item pointers */
 		tids = ginPostingListDecode(cur, &ndecoded);
-		tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+		tids_datum = palloc_array(Datum, ndecoded);
 		for (i = 0; i < ndecoded; i++)
 			tids_datum[i] = ItemPointerGetDatum(&tids[i]);
 		values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
-- 
2.43.0

From fe73b3197548d813ce232ce76a507fad8d87b7b2 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v12 2/2] GIN pageinspect support for entry tree and posting
 tree internal pages

This patch provides a new version for the pageinspect contrib module, including
two new functions:

* gin_entrypage_items.

* gin_datapage_items.

These two functions can be used to examine the GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used for both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine the non-leaf posting tree pages.

We keep the different functions here mainly because of different GIN.
pages layoff.

Note that fast-list pages are out of scope of this patch.

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Roman Khapov <rkhapov@yandex-team.ru>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 350 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 699 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..5018ef76aa7 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support metapages
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  gin_entrypage_items does not support posting tree pages
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..afb52500111
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]--------
+itemoffset | 1
+downlink   | 4
+item_tid   | (41,125)
+-[ RECORD 2 ]--------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support metapages
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  gin_entrypage_items does not support posting tree pages
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 136
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index b7bd7a3f4cd..baaf0b21436 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,347 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+/*
+ * gin_entrypage_items
+ *
+ * Allows inspection of contents of an entry tree page.
+ */
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid			indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation	indexRel;
+	OffsetNumber maxoff;
+	TupleDesc	tupdesc;
+	Page		page;
+	GinPageOpaque opaq;
+	StringInfoData buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a %s index",
+					   RelationGetRelationName(indexRel), "GIN"));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN entry tree page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  PageGetSpecialSize(page)));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support metapages"));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support fast list pages"));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support posting tree pages"),
+				errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber indAtt;
+		Datum		values[4];
+		bool		nulls[4] = {0};
+		Datum		attrVal;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			ereport(ERROR, errcode(ERRCODE_INDEX_CORRUPTED), errmsg("invalid ItemId at offset %u", offset));
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (tupdesc->natts == 1)
+		{
+			indAtt = FirstOffsetNumber;
+
+			/* Here we can safely reuse any tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %u", offset));
+		}
+		else
+		{
+			TupleDesc	tmpTupdesc;
+			Datum		res;
+			Form_pg_attribute attr;
+
+			/*
+			 * Multi-column GIN indexes store 2-attribute tuple on each page
+			 * item. First attribute is which heap attribute is stored as the
+			 * second value in pair. To display value with proper output
+			 * function we need to recreate tuple descriptor on each offset.
+			 */
+
+			/* orig tuple reuse is safe */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+
+			/*
+			 * we do not expect null for first attr in multi-column GIN
+			 */
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %u", offset));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+									tmpTupdesc,
+									&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull)
+		{
+			Oid			foutoid;
+			bool		typisvarlena;
+			Oid			typoid;
+			char	   *value;
+			bool		nq;
+
+			/*
+			 * The following value output and quoting logic is copied from
+			 * record_out().
+			 */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			int			ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool		free_items_orig;
+
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+/*
+ * gin_datapage_items
+ *
+ * Allows inspection of contents of an posting tree non-leaf page.
+ */
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("input page is not a valid GIN data leaf page"),
+				 errdetail("Expected special size %d, got %d.",
+						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						   (int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/*
+	 * Reject non-entry-tree GIN pages, which are metapage, fastlist pages,
+	 * and posting tree pages.
+	 */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_datapage_items is unsupported for GIN fast update list"));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN data tree page"));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is a GIN data leaf tree page"),
+				errhint("This appears to be a GIN posting leaf tree page. Please use gin_leafpage_items."));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem *item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From cca4b1eaecb36cbb28ef79c1d7d560d5740e15f6 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Wed, 7 Jan 2026 19:38:52 +0000
Subject: [PATCH v12 1/2] Modernize coding in GIN pageinspect functions.

This patch switches palloc to our newly preferred palloc_array and modernizes
ereport calls, switching from list-style to polymorphic ereport
calls. This patch also fixes whitespace/tab issues, enforcing a single style.
across existing ginfuncs.c code.

Inspired by Peter Eisentraut's patch in the thread.

Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/ginfuncs.c | 58 +++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..b7bd7a3f4cd 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -38,8 +38,8 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -48,20 +48,20 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN metapage"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN metapage"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
 	if (opaq->flags != GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a GIN metapage"),
-				 errdetail("Flags %04X, expected %04X",
-						   opaq->flags, GIN_META)));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN metapage"),
+				errdetail("Flags %04X, expected %04X",
+						  opaq->flags, GIN_META));
 
 	/* Build a tuple descriptor for our result type */
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
@@ -118,11 +118,11 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN data leaf page"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
@@ -184,8 +184,8 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	if (SRF_IS_FIRSTCALL())
 	{
@@ -207,20 +207,20 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a valid GIN data leaf page"),
-					 errdetail("Expected special size %d, got %d.",
-							   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							   (int) PageGetSpecialSize(page))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							  (int) PageGetSpecialSize(page)));
 
 		opaq = GinPageGetOpaque(page);
 		if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a compressed GIN data leaf page"),
-					 errdetail("Flags %04X, expected %04X",
-							   opaq->flags,
-							   (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a compressed GIN data leaf page"),
+					errdetail("Flags %04X, expected %04X",
+							  opaq->flags,
+							  (GIN_DATA | GIN_LEAF | GIN_COMPRESSED)));
 
 		inter_call_data = palloc_object(gin_leafpage_items_state);
 
@@ -262,7 +262,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		/* build an array of decoded item pointers */
 		tids = ginPostingListDecode(cur, &ndecoded);
-		tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+		tids_datum = palloc_array(Datum, ndecoded);
 		for (i = 0; i < ndecoded; i++)
 			tids_datum[i] = ItemPointerGetDatum(&tids[i]);
 		values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
-- 
2.43.0

From cca4b1eaecb36cbb28ef79c1d7d560d5740e15f6 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Wed, 7 Jan 2026 19:38:52 +0000
Subject: [PATCH v13 1/2] Modernize coding in GIN pageinspect functions.

This patch switches palloc to our newly preferred palloc_array and modernizes
ereport calls, switching from list-style to polymorphic ereport
calls. This patch also fixes whitespace/tab issues, enforcing a single style.
across existing ginfuncs.c code.

Inspired by Peter Eisentraut's patch in the thread.

Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/ginfuncs.c | 58 +++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..b7bd7a3f4cd 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -38,8 +38,8 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -48,20 +48,20 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN metapage"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN metapage"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
 	if (opaq->flags != GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a GIN metapage"),
-				 errdetail("Flags %04X, expected %04X",
-						   opaq->flags, GIN_META)));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN metapage"),
+				errdetail("Flags %04X, expected %04X",
+						  opaq->flags, GIN_META));
 
 	/* Build a tuple descriptor for our result type */
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
@@ -118,11 +118,11 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN data leaf page"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
@@ -184,8 +184,8 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	if (SRF_IS_FIRSTCALL())
 	{
@@ -207,20 +207,20 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a valid GIN data leaf page"),
-					 errdetail("Expected special size %d, got %d.",
-							   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							   (int) PageGetSpecialSize(page))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							  (int) PageGetSpecialSize(page)));
 
 		opaq = GinPageGetOpaque(page);
 		if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a compressed GIN data leaf page"),
-					 errdetail("Flags %04X, expected %04X",
-							   opaq->flags,
-							   (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a compressed GIN data leaf page"),
+					errdetail("Flags %04X, expected %04X",
+							  opaq->flags,
+							  (GIN_DATA | GIN_LEAF | GIN_COMPRESSED)));
 
 		inter_call_data = palloc_object(gin_leafpage_items_state);
 
@@ -262,7 +262,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		/* build an array of decoded item pointers */
 		tids = ginPostingListDecode(cur, &ndecoded);
-		tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+		tids_datum = palloc_array(Datum, ndecoded);
 		for (i = 0; i < ndecoded; i++)
 			tids_datum[i] = ItemPointerGetDatum(&tids[i]);
 		values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
-- 
2.43.0

From 1c0ea0cca057af45cdc8c44b197ce76de5bf6732 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v13 2/2] GIN pageinspect support for entry tree and posting
 tree internal pages

This patch provides a new version for the pageinspect contrib module, including
two new functions:

* gin_entrypage_items.

* gin_datapage_items.

These two functions can be used to examine the GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used for both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine the non-leaf posting tree pages.

We keep the different functions here mainly because of different GIN.
pages layoff.

Note that fast-list pages are out of scope of this patch.

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Roman Khapov <rkhapov@yandex-team.ru>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 350 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 699 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..5018ef76aa7 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support metapages
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  gin_entrypage_items does not support posting tree pages
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..afb52500111
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]--------
+itemoffset | 1
+downlink   | 4
+item_tid   | (41,125)
+-[ RECORD 2 ]--------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support metapages
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  gin_entrypage_items does not support posting tree pages
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 136
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index b7bd7a3f4cd..c9cf08872ac 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,347 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+/*
+ * gin_entrypage_items
+ *
+ * Allows inspection of contents of an entry tree page.
+ */
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid			indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation	indexRel;
+	OffsetNumber maxoff;
+	TupleDesc	tupdesc;
+	Page		page;
+	GinPageOpaque opaq;
+	StringInfoData buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the index relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a %s index",
+					   RelationGetRelationName(indexRel), "GIN"));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN entry tree page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support metapages"));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support fast list pages"));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support posting tree pages"),
+				errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber indAtt;
+		Datum		values[4];
+		bool		nulls[4] = {0};
+		Datum		attrVal;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			ereport(ERROR, errcode(ERRCODE_INDEX_CORRUPTED), errmsg("invalid ItemId at offset %u", offset));
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (tupdesc->natts == 1)
+		{
+			indAtt = FirstOffsetNumber;
+
+			/* Here we can safely reuse any tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %u", offset));
+		}
+		else
+		{
+			TupleDesc	tmpTupdesc;
+			Datum		res;
+			Form_pg_attribute attr;
+
+			/*
+			 * Multi-column GIN indexes store 2-attribute tuple on each page
+			 * item. First attribute is which heap attribute is stored as the
+			 * second value in pair. To display value with proper output
+			 * function we need to recreate tuple descriptor on each offset.
+			 * NB: It is safe to reuse the original index tuple. See also
+			 * gintuple_get_attrnum.
+			 */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+
+			/*
+			 * we do not expect null for first attr in multi-column GIN
+			 */
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %u", offset));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+									tmpTupdesc,
+									&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull)
+		{
+			Oid			foutoid;
+			bool		typisvarlena;
+			Oid			typoid;
+			char	   *value;
+			bool		nq;
+
+			/*
+			 * The following value output and quoting logic is copied from
+			 * record_out().
+			 */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			int			ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool		free_items_orig;
+
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+/*
+ * gin_datapage_items
+ *
+ * Allows inspection of contents of an posting tree non-leaf page.
+ */
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("input page is not a valid GIN data leaf page"),
+				 errdetail("Expected special size %d, got %d.",
+						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						   (int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/*
+	 * Reject non-entry-tree GIN pages, which are metapage, fastlist pages,
+	 * and posting tree pages.
+	 */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_datapage_items is unsupported for GIN fast update list"));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN data tree page"));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is a GIN data leaf tree page"),
+				errhint("This appears to be a GIN posting leaf tree page. Please use gin_leafpage_items."));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem *item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From e294f67635175d86c9c0a864eabc52b353eace61 Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Wed, 7 Jan 2026 19:38:52 +0000
Subject: [PATCH v14 1/3] Modernize coding in GIN pageinspect functions.

This patch switches palloc to our newly preferred palloc_array and modernizes
ereport calls, switching from list-style to polymorphic ereport
calls. This patch also fixes whitespace/tab issues, enforcing a single style.
across existing ginfuncs.c code.

Inspired by Peter Eisentraut's patch in the thread.

Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/ginfuncs.c | 58 +++++++++++++++++-----------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index ebcc2b3db5c..b7bd7a3f4cd 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -38,8 +38,8 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	page = get_page_from_raw(raw_page);
 
@@ -48,20 +48,20 @@ gin_metapage_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN metapage"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN metapage"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
 	if (opaq->flags != GIN_META)
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a GIN metapage"),
-				 errdetail("Flags %04X, expected %04X",
-						   opaq->flags, GIN_META)));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN metapage"),
+				errdetail("Flags %04X, expected %04X",
+						  opaq->flags, GIN_META));
 
 	/* Build a tuple descriptor for our result type */
 	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
@@ -118,11 +118,11 @@ gin_page_opaque_info(PG_FUNCTION_ARGS)
 
 	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("input page is not a valid GIN data leaf page"),
-				 errdetail("Expected special size %d, got %d.",
-						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-						   (int) PageGetSpecialSize(page))));
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN data leaf page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
 
 	opaq = GinPageGetOpaque(page);
 
@@ -184,8 +184,8 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 	if (!superuser())
 		ereport(ERROR,
-				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-				 errmsg("must be superuser to use raw page functions")));
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
 
 	if (SRF_IS_FIRSTCALL())
 	{
@@ -207,20 +207,20 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a valid GIN data leaf page"),
-					 errdetail("Expected special size %d, got %d.",
-							   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
-							   (int) PageGetSpecialSize(page))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a valid GIN data leaf page"),
+					errdetail("Expected special size %d, got %d.",
+							  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+							  (int) PageGetSpecialSize(page)));
 
 		opaq = GinPageGetOpaque(page);
 		if (opaq->flags != (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))
 			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("input page is not a compressed GIN data leaf page"),
-					 errdetail("Flags %04X, expected %04X",
-							   opaq->flags,
-							   (GIN_DATA | GIN_LEAF | GIN_COMPRESSED))));
+					errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					errmsg("input page is not a compressed GIN data leaf page"),
+					errdetail("Flags %04X, expected %04X",
+							  opaq->flags,
+							  (GIN_DATA | GIN_LEAF | GIN_COMPRESSED)));
 
 		inter_call_data = palloc_object(gin_leafpage_items_state);
 
@@ -262,7 +262,7 @@ gin_leafpage_items(PG_FUNCTION_ARGS)
 
 		/* build an array of decoded item pointers */
 		tids = ginPostingListDecode(cur, &ndecoded);
-		tids_datum = (Datum *) palloc(ndecoded * sizeof(Datum));
+		tids_datum = palloc_array(Datum, ndecoded);
 		for (i = 0; i < ndecoded; i++)
 			tids_datum[i] = ItemPointerGetDatum(&tids[i]);
 		values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
-- 
2.43.0

From f65c8c9bd59936aa05415574ed5183c72622994e Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Mon, 13 Oct 2025 20:14:26 +0000
Subject: [PATCH v14 2/3] GIN pageinspect support for entry tree and posting
 tree internal pages

This patch provides a new version for the pageinspect contrib module, including
two new functions:

* gin_entrypage_items.

* gin_datapage_items.

These two functions can be used to examine the GIN entry tree and posting
tree pages. Namely, gin_entrypage_items can be used for both leaf and
non-leaf entry tree pages. gin_datapage_items is provided in pairs with
already-existing gin_leafpage_items to examine the non-leaf posting tree pages.

We keep the different functions here mainly because of different GIN.
pages layoff.

Note that fast-list pages are out of scope of this patch.

Co-authored-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Reviewed-by: Roman Khapov <rkhapov@yandex-team.ru>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/Makefile                  |   2 +-
 contrib/pageinspect/expected/gin.out          |  84 ++++-
 contrib/pageinspect/expected/gin_1.out        | 151 ++++++++
 contrib/pageinspect/ginfuncs.c                | 350 ++++++++++++++++++
 contrib/pageinspect/meson.build               |   1 +
 .../pageinspect/pageinspect--1.13--1.14.sql   |  27 ++
 contrib/pageinspect/pageinspect.control       |   2 +-
 contrib/pageinspect/sql/gin.sql               |  34 +-
 doc/src/sgml/pageinspect.sgml                 |  54 +++
 9 files changed, 699 insertions(+), 6 deletions(-)
 create mode 100644 contrib/pageinspect/expected/gin_1.out
 create mode 100644 contrib/pageinspect/pageinspect--1.13--1.14.sql

diff --git a/contrib/pageinspect/Makefile b/contrib/pageinspect/Makefile
index eae989569d0..09774fd340c 100644
--- a/contrib/pageinspect/Makefile
+++ b/contrib/pageinspect/Makefile
@@ -13,7 +13,7 @@ OBJS = \
 	rawpage.o
 
 EXTENSION = pageinspect
-DATA =  pageinspect--1.12--1.13.sql \
+DATA =  pageinspect--1.13--1.14.sql pageinspect--1.12--1.13.sql \
 	pageinspect--1.11--1.12.sql pageinspect--1.10--1.11.sql \
 	pageinspect--1.9--1.10.sql pageinspect--1.8--1.9.sql \
 	pageinspect--1.7--1.8.sql pageinspect--1.6--1.7.sql \
diff --git a/contrib/pageinspect/expected/gin.out b/contrib/pageinspect/expected/gin.out
index ff1da6a5a17..5018ef76aa7 100644
--- a/contrib/pageinspect/expected/gin.out
+++ b/contrib/pageinspect/expected/gin.out
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 \x
 SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
 -[ RECORD 1 ]----+-----------
@@ -27,6 +29,45 @@ flags     | {leaf}
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 ERROR:  input page is not a compressed GIN data leaf page
 DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 SELECT COUNT(*) > 0
 FROM gin_leafpage_items(get_raw_page('test1_y_idx',
@@ -35,6 +76,23 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
 -[ RECORD 1 ]
 ?column? | t
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]-------
+itemoffset | 1
+downlink   | 4
+item_tid   | (44,83)
+-[ RECORD 2 ]-------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -54,12 +112,34 @@ ERROR:  input page is not a valid GIN data leaf page
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 ERROR:  input page is not a valid GIN data leaf page
 \set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support metapages
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  gin_entrypage_items does not support posting tree pages
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 120
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support fast list pages
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]------+-
 gin_leafpage_items | 
 
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 -[ RECORD 1 ]-----+-
 gin_metapage_info | 
diff --git a/contrib/pageinspect/expected/gin_1.out b/contrib/pageinspect/expected/gin_1.out
new file mode 100644
index 00000000000..afb52500111
--- /dev/null
+++ b/contrib/pageinspect/expected/gin_1.out
@@ -0,0 +1,151 @@
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
+\x
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 0));
+-[ RECORD 1 ]----+-----------
+pending_head     | 4294967295
+pending_tail     | 4294967295
+tail_free_size   | 0
+n_pending_pages  | 0
+n_pending_tuples | 0
+n_total_pages    | 2
+n_entry_pages    | 1
+n_data_pages     | 0
+n_entries        | 2
+version          | 2
+
+SELECT * FROM gin_metapage_info(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a GIN metapage
+DETAIL:  Flags 0002, expected 0008
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
+-[ RECORD 1 ]---------
+rightlink | 4294967295
+maxoff    | 0
+flags     | {leaf}
+
+SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
+ERROR:  input page is not a compressed GIN data leaf page
+DETAIL:  Flags 0002, expected 0083
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | y=111
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+-[ RECORD 1 ]--------------
+itemoffset | 1
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=11
+-[ RECORD 2 ]--------------
+itemoffset | 2
+downlink   | (2147483664,1)
+tids       | {"(0,1)"}
+keys       | y=111
+-[ RECORD 3 ]--------------
+itemoffset | 3
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=a
+-[ RECORD 4 ]--------------
+itemoffset | 4
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=b
+-[ RECORD 5 ]--------------
+itemoffset | 5
+downlink   | (2147483660,1)
+tids       | {"(0,1)"}
+keys       | z=c
+
+INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
+SELECT COUNT(*) > 0
+FROM gin_leafpage_items(get_raw_page('test1_y_idx',
+                        (pg_relation_size('test1_y_idx') /
+                         current_setting('block_size')::bigint)::int - 1));
+-[ RECORD 1 ]
+?column? | t
+
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+-[ RECORD 1 ]--------
+itemoffset | 1
+downlink   | 4
+item_tid   | (41,125)
+-[ RECORD 2 ]--------
+itemoffset | 2
+downlink   | 3
+item_tid   | (0,0)
+
+-- Failure with various modes.
+-- Suppress the DETAIL message, to allow the tests to work across various
+-- page sizes and architectures.
+\set VERBOSITY terse
+-- invalid page size
+SELECT gin_leafpage_items('aaa'::bytea);
+ERROR:  invalid page size
+SELECT gin_metapage_info('bbb'::bytea);
+ERROR:  invalid page size
+SELECT gin_page_opaque_info('ccc'::bytea);
+ERROR:  invalid page size
+-- invalid special area size
+SELECT * FROM gin_metapage_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN metapage
+SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
+ERROR:  input page is not a valid GIN data leaf page
+\set VERBOSITY default
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support metapages
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+ERROR:  gin_entrypage_items does not support posting tree pages
+HINT:  This appears to be a GIN posting tree page. Please use gin_datapage_items.
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-[ RECORD 1 ]------------------
+rightlink | 3
+maxoff    | 136
+flags     | {list,list_fullrow}
+
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+ERROR:  gin_entrypage_items does not support fast list pages
+-- Tests with all-zero pages.
+SHOW block_size \gset
+SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]------+-
+gin_leafpage_items | 
+
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
+(0 rows)
+
+SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]-----+-
+gin_metapage_info | 
+
+SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
+-[ RECORD 1 ]--------+-
+gin_page_opaque_info | 
+
+DROP TABLE test1;
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index b7bd7a3f4cd..c9cf08872ac 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -11,18 +11,27 @@
 
 #include "access/gin_private.h"
 #include "access/htup_details.h"
+#include "access/relation.h"
+#include "access/tupdesc.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pageinspect.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/ruleutils.h"
 
 
 PG_FUNCTION_INFO_V1(gin_metapage_info);
 PG_FUNCTION_INFO_V1(gin_page_opaque_info);
+PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
+PG_FUNCTION_INFO_V1(gin_datapage_items);
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+#define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
 gin_metapage_info(PG_FUNCTION_ARGS)
@@ -175,6 +184,347 @@ typedef struct gin_leafpage_items_state
 	GinPostingList *lastseg;
 } gin_leafpage_items_state;
 
+/*
+ * gin_entrypage_items
+ *
+ * Allows inspection of contents of an entry tree page.
+ */
+Datum
+gin_entrypage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	Oid			indexRelid = PG_GETARG_OID(1);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	Relation	indexRel;
+	OffsetNumber maxoff;
+	TupleDesc	tupdesc;
+	Page		page;
+	GinPageOpaque opaq;
+	StringInfoData buf;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+
+	/* Open the index relation */
+	indexRel = index_open(indexRelid, AccessShareLock);
+
+	if (!IS_INDEX(indexRel) || !IS_GIN(indexRel))
+		ereport(ERROR,
+				errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				errmsg("\"%s\" is not a %s index",
+					   RelationGetRelationName(indexRel), "GIN"));
+
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		index_close(indexRel, AccessShareLock);
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a valid GIN entry tree page"),
+				errdetail("Expected special size %d, got %d.",
+						  (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						  (int) PageGetSpecialSize(page)));
+
+	opaq = GinPageGetOpaque(page);
+
+	/* we only support entry tree in this function, check that */
+	if (opaq->flags & GIN_META)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support metapages"));
+
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support fast list pages"));
+
+
+	if (opaq->flags & GIN_DATA)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_entrypage_items does not support posting tree pages"),
+				errhint("This appears to be a GIN posting tree page. Please use gin_datapage_items."));
+
+	initStringInfo(&buf);
+	maxoff = PageGetMaxOffsetNumber(page);
+
+	tupdesc = RelationGetDescr(indexRel);
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		OffsetNumber indAtt;
+		Datum		values[4];
+		bool		nulls[4] = {0};
+		Datum		attrVal;
+		bool		isnull;
+		IndexTuple	idxtuple;
+		ItemId		iid = PageGetItemId(page, offset);
+
+		if (!ItemIdIsValid(iid))
+			ereport(ERROR, errcode(ERRCODE_INDEX_CORRUPTED), errmsg("invalid ItemId at offset %u", offset));
+
+		idxtuple = (IndexTuple) PageGetItem(page, iid);
+
+		values[0] = UInt16GetDatum(offset);
+
+		if (tupdesc->natts == 1)
+		{
+			indAtt = FirstOffsetNumber;
+
+			/* Here we can safely reuse any tuple descriptor. */
+			attrVal = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %u", offset));
+		}
+		else
+		{
+			TupleDesc	tmpTupdesc;
+			Datum		res;
+			Form_pg_attribute attr;
+
+			/*
+			 * Multi-column GIN indexes store 2-attribute tuple on each page
+			 * item. First attribute is which heap attribute is stored as the
+			 * second value in pair. To display value with proper output
+			 * function we need to recreate tuple descriptor on each offset.
+			 * NB: It is safe to reuse the original index tuple. See also
+			 * gintuple_get_attrnum.
+			 */
+
+			res = index_getattr(idxtuple, FirstOffsetNumber, tupdesc, &isnull);
+
+			/*
+			 * we do not expect null for first attr in multi-column GIN
+			 */
+			if (isnull)
+				ereport(ERROR,
+						errcode(ERRCODE_INDEX_CORRUPTED),
+						errmsg("invalid gin entry page tuple at offset %u", offset));
+
+			indAtt = DatumGetUInt16(res);
+
+			attr = TupleDescAttr(tupdesc, indAtt - 1);
+
+			tmpTupdesc = CreateTemplateTupleDesc(2);
+
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 1, NULL,
+							   INT2OID, -1, 0);
+			TupleDescInitEntry(tmpTupdesc, (AttrNumber) 2, NULL,
+							   attr->atttypid,
+							   attr->atttypmod,
+							   attr->attndims);
+			TupleDescInitEntryCollation(tmpTupdesc, (AttrNumber) 2,
+										attr->attcollation);
+
+			attrVal = index_getattr(idxtuple, OffsetNumberNext(FirstOffsetNumber),
+									tmpTupdesc,
+									&isnull);
+
+			FreeTupleDesc(tmpTupdesc);
+		}
+
+		appendStringInfo(&buf, "%s=", quote_identifier(TupleDescAttr(tupdesc, indAtt - 1)->attname.data));
+
+		if (!isnull)
+		{
+			Oid			foutoid;
+			bool		typisvarlena;
+			Oid			typoid;
+			char	   *value;
+			bool		nq;
+
+			/*
+			 * The following value output and quoting logic is copied from
+			 * record_out().
+			 */
+			typoid = TupleDescAttr(tupdesc, indAtt - 1)->atttypid;
+			getTypeOutputInfo(typoid, &foutoid, &typisvarlena);
+			value = OidOutputFunctionCall(foutoid, attrVal);
+
+			/* Check whether we need double quotes for this value */
+			nq = (value[0] == '\0');	/* force quotes for empty string */
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\' ||
+					ch == '(' || ch == ')' || ch == ',' ||
+					isspace((unsigned char) ch))
+				{
+					nq = true;
+					break;
+				}
+			}
+
+			/* And emit the string */
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+			for (const char *tmp = value; *tmp; tmp++)
+			{
+				char		ch = *tmp;
+
+				if (ch == '"' || ch == '\\')
+					appendStringInfoCharMacro(&buf, ch);
+				appendStringInfoCharMacro(&buf, ch);
+			}
+			if (nq)
+				appendStringInfoCharMacro(&buf, '"');
+		}
+		else
+		{
+			appendStringInfo(&buf, "NULL");
+		}
+
+		values[3] = CStringGetTextDatum(buf.data);
+		resetStringInfo(&buf);
+
+		if (GinIsPostingTree(idxtuple))
+		{
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			nulls[2] = true;
+		}
+		else
+		{
+			int			ndecoded;
+			Datum	   *tids_datum;
+			ItemPointer items_orig;
+			bool		free_items_orig;
+
+			values[1] = ItemPointerGetDatum(&idxtuple->t_tid);
+			/* Get list of item pointers from the tuple. */
+			if (GinItupIsCompressed(idxtuple))
+			{
+				items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(idxtuple), &ndecoded);
+				free_items_orig = true;
+			}
+			else
+			{
+				items_orig = (ItemPointer) GinGetPosting(idxtuple);
+				ndecoded = GinGetNPosting(idxtuple);
+				free_items_orig = false;
+			}
+
+			tids_datum = palloc_array(Datum, ndecoded);
+			for (int i = 0; i < ndecoded; i++)
+				tids_datum[i] = ItemPointerGetDatum(&items_orig[i]);
+			values[2] = PointerGetDatum(construct_array_builtin(tids_datum, ndecoded, TIDOID));
+
+			pfree(tids_datum);
+
+			if (free_items_orig)
+				pfree(items_orig);
+		}
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	index_close(indexRel, AccessShareLock);
+
+	return (Datum) 0;
+}
+
+/*
+ * gin_datapage_items
+ *
+ * Allows inspection of contents of an posting tree non-leaf page.
+ */
+Datum
+gin_datapage_items(PG_FUNCTION_ARGS)
+{
+	bytea	   *raw_page = PG_GETARG_BYTEA_P(0);
+	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+	OffsetNumber maxoff;
+	Page		page;
+	GinPageOpaque opaq;
+
+	if (!superuser())
+		ereport(ERROR,
+				errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				errmsg("must be superuser to use raw page functions"));
+
+	InitMaterializedSRF(fcinfo, 0);
+	page = get_page_from_raw(raw_page);
+
+	if (PageIsNew(page))
+	{
+		PG_RETURN_NULL();
+	}
+
+	if (PageGetSpecialSize(page) != MAXALIGN(sizeof(GinPageOpaqueData)))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("input page is not a valid GIN data leaf page"),
+				 errdetail("Expected special size %d, got %d.",
+						   (int) MAXALIGN(sizeof(GinPageOpaqueData)),
+						   (int) PageGetSpecialSize(page))));
+
+	opaq = GinPageGetOpaque(page);
+
+	/*
+	 * Reject non-entry-tree GIN pages, which are metapage, fastlist pages,
+	 * and posting tree pages.
+	 */
+
+	if (opaq->flags & (GIN_META))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("gin_datapage_items is unsupported for metapage")));
+
+	if (opaq->flags & (GIN_LIST | GIN_LIST_FULLROW))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("gin_datapage_items is unsupported for GIN fast update list"));
+
+	if (!(opaq->flags & GIN_DATA))
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is not a GIN data tree page"));
+
+	if (opaq->flags & GIN_LEAF)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("input page is a GIN data leaf tree page"),
+				errhint("This appears to be a GIN posting leaf tree page. Please use gin_leafpage_items."));
+
+	maxoff = GinPageGetOpaque(page)->maxoff;
+
+	for (OffsetNumber offset = FirstOffsetNumber;
+		 offset <= maxoff;
+		 offset = OffsetNumberNext(offset))
+	{
+		Datum		values[3];
+		bool		nulls[3];
+		PostingItem *item = GinDataPageGetPostingItem(page, offset);
+
+		memset(nulls, 0, sizeof(nulls));
+
+		values[0] = UInt16GetDatum(offset);
+
+		values[1] = UInt32GetDatum(BlockIdGetBlockNumber(&item->child_blkno));
+		values[2] = ItemPointerGetDatum(&item->key);
+
+		/* Build and return the result tuple. */
+		tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+	}
+
+	return (Datum) 0;
+}
+
 Datum
 gin_leafpage_items(PG_FUNCTION_ARGS)
 {
diff --git a/contrib/pageinspect/meson.build b/contrib/pageinspect/meson.build
index c43ea400a4d..2f333635838 100644
--- a/contrib/pageinspect/meson.build
+++ b/contrib/pageinspect/meson.build
@@ -38,6 +38,7 @@ install_data(
   'pageinspect--1.10--1.11.sql',
   'pageinspect--1.11--1.12.sql',
   'pageinspect--1.12--1.13.sql',
+  'pageinspect--1.13--1.14.sql',
   'pageinspect.control',
   kwargs: contrib_data_args,
 )
diff --git a/contrib/pageinspect/pageinspect--1.13--1.14.sql b/contrib/pageinspect/pageinspect--1.13--1.14.sql
new file mode 100644
index 00000000000..ef6fa87e0f4
--- /dev/null
+++ b/contrib/pageinspect/pageinspect--1.13--1.14.sql
@@ -0,0 +1,27 @@
+/* contrib/pageinspect/pageinspect--1.13--1.14.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pageinspect UPDATE TO '1.14'" to load this file. \quit
+
+--
+-- gin_entrypage_items()
+--
+CREATE FUNCTION gin_entrypage_items(IN page bytea, IN reloid OID,
+    OUT itemoffset smallint,
+    OUT downlink tid,
+    OUT tids tid[],
+    OUT keys text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_entrypage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- gin_datapage_items()
+--
+CREATE FUNCTION gin_datapage_items(IN page bytea,
+    OUT itemoffset smallint,
+    OUT downlink int,
+    OUT item_tid tid)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'gin_datapage_items'
+LANGUAGE C STRICT PARALLEL SAFE;
diff --git a/contrib/pageinspect/pageinspect.control b/contrib/pageinspect/pageinspect.control
index cfc87feac03..aee3f598a9e 100644
--- a/contrib/pageinspect/pageinspect.control
+++ b/contrib/pageinspect/pageinspect.control
@@ -1,5 +1,5 @@
 # pageinspect extension
 comment = 'inspect the contents of database pages at a low level'
-default_version = '1.13'
+default_version = '1.14'
 module_pathname = '$libdir/pageinspect'
 relocatable = true
diff --git a/contrib/pageinspect/sql/gin.sql b/contrib/pageinspect/sql/gin.sql
index b57466d7ebf..1a9eaebeebc 100644
--- a/contrib/pageinspect/sql/gin.sql
+++ b/contrib/pageinspect/sql/gin.sql
@@ -1,6 +1,8 @@
-CREATE TABLE test1 (x int, y int[]);
-INSERT INTO test1 VALUES (1, ARRAY[11, 111]);
+CREATE TABLE test1 (x int, y int[], z text[]);
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
 CREATE INDEX test1_y_idx ON test1 USING gin (y) WITH (fastupdate = off);
+CREATE INDEX test2_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = off);
+CREATE INDEX test3_y_z_idx ON test1 USING gin (y, z) WITH (fastupdate = on);
 
 \x
 
@@ -11,6 +13,10 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1_y_idx', 1));
 
 SELECT * FROM gin_leafpage_items(get_raw_page('test1_y_idx', 1));
 
+SELECT * FROM gin_entrypage_items(get_raw_page('test1_y_idx', 1), 'test1_y_idx'::regclass);
+
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 1), 'test2_y_z_idx'::regclass);
+
 INSERT INTO test1 SELECT x, ARRAY[1,10] FROM generate_series(2,10000) x;
 
 SELECT COUNT(*) > 0
@@ -18,6 +24,18 @@ FROM gin_leafpage_items(get_raw_page('test1_y_idx',
                         (pg_relation_size('test1_y_idx') /
                          current_setting('block_size')::bigint)::int - 1));
 
+-- Now test posting tree non-leaf page.
+-- This requires inserting many tuples on a single leaf page to trigger page split.
+
+CREATE TABLE test_data_page(i INT[]);
+CREATE INDEX test_data_page_i_idx ON test_data_page USING gin(i) WITH (fastupdate = off);
+
+INSERT INTO test_data_page SELECT ARRAY[1] FROM generate_series(1, 10000);
+
+-- For this index, block 0 is metapage, block 1 is entry tree, block 2 is
+-- posting tree non-leaf page and block 3 & 4 are compressed data leaf pages.
+SELECT * FROM gin_datapage_items(get_raw_page('test_data_page_i_idx', 2));
+
 -- Failure with various modes.
 -- Suppress the DETAIL message, to allow the tests to work across various
 -- page sizes and architectures.
@@ -32,9 +50,21 @@ SELECT * FROM gin_page_opaque_info(get_raw_page('test1', 0));
 SELECT * FROM gin_leafpage_items(get_raw_page('test1', 0));
 \set VERBOSITY default
 
+-- Reject unsupported page types in gin_entrypage_items.
+SELECT * FROM gin_entrypage_items(get_raw_page('test2_y_z_idx', 0), 'test2_y_z_idx'::regclass);
+-- Check the error message for the internal posting tree page.
+SELECT * FROM gin_entrypage_items(get_raw_page('test_data_page_i_idx', 2), 'test_data_page_i_idx'::regclass);
+-- insert new row to trigger new (fast-list) page allocation.
+INSERT INTO test1 VALUES (1, ARRAY[11, 111], ARRAY['a', 'b', 'c']);
+-- double check that the new page is fast-list.
+SELECT * FROM gin_page_opaque_info(get_raw_page('test3_y_z_idx', 2));
+-- reject fast-list pages.
+SELECT * FROM gin_entrypage_items(get_raw_page('test3_y_z_idx', 3), 'test3_y_z_idx'::regclass);
+
 -- Tests with all-zero pages.
 SHOW block_size \gset
 SELECT gin_leafpage_items(decode(repeat('00', :block_size), 'hex'));
+SELECT gin_datapage_items(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_metapage_info(decode(repeat('00', :block_size), 'hex'));
 SELECT gin_page_opaque_info(decode(repeat('00', :block_size), 'hex'));
 
diff --git a/doc/src/sgml/pageinspect.sgml b/doc/src/sgml/pageinspect.sgml
index 3a113439e1d..4ed8826e92e 100644
--- a/doc/src/sgml/pageinspect.sgml
+++ b/doc/src/sgml/pageinspect.sgml
@@ -714,6 +714,60 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
  (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
  (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
 (7 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_entrypage_items(page bytea, reloid oid) returns setof record</function>
+     <indexterm>
+      <primary>gin_entrypage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_entrypage_items</function> returns information about
+      the data stored in a entry tree <acronym>GIN</acronym> page.  For example:
+<screen>
+test=# select * from gin_entrypage_items(get_raw_page('gin_test_idx',
+1), 'gin_test_idx'::regclass);
+ itemoffset | downlink | tids |                keys
+------------+----------+------+------------------------------------
+          1 | (3,0)    | {}   | i=113
+          2 | (5,0)    | {}   | j=34173cb38f07f89ddbebc2ac9128303f
+          3 | (2,0)    | {}   | j=a0a080f42e6f13b3a2df133f073095dd
+          4 | (4,0)    | {}   | j=fc490ca45c00b1249bbe3554a4fdf6fb
+(4 rows)
+</screen>
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term>
+     <function>gin_datapage_items(page bytea) returns setof record</function>
+     <indexterm>
+      <primary>gin_datapage_items</primary>
+     </indexterm>
+    </term>
+
+    <listitem>
+     <para>
+      <function>gin_datapage_items</function> returns information about
+      the data stored in a posting tree <acronym>GIN</acronym> internal page.  For example:
+<screen>
+test=# select * from gin_datapage_items(get_raw_page('gin_test_idx',
+43));
+ itemoffset | downlink | item_tid
+------------+----------+----------
+          1 |      124 | (162,12)
+          2 |      123 | (314,37)
+          3 |      251 | (467,23)
+          4 |      373 | (0,0)
+(4 rows)
 </screen>
      </para>
     </listitem>
-- 
2.43.0

From f90043e70b6816727c1dac80250349b14b019b8a Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Sat, 10 Jan 2026 14:11:37 +0000
Subject: [PATCH v14 3/3] Move IS_INDEX macro to pageinspect.h

Suggested-by: Japin Li <japinli@hotmail.com>

Discussion: https://postgr.es/m/CALdSSPiN13n7feQcY0WCmq8jzxjwqhNrt1E=g=g6aZANyE_OoQ@mail.gmail.com
---
 contrib/pageinspect/btreefuncs.c  | 1 -
 contrib/pageinspect/ginfuncs.c    | 1 -
 contrib/pageinspect/hashfuncs.c   | 1 -
 contrib/pageinspect/pageinspect.h | 2 ++
 4 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/contrib/pageinspect/btreefuncs.c b/contrib/pageinspect/btreefuncs.c
index 62c905c6e7c..b8a0428ed19 100644
--- a/contrib/pageinspect/btreefuncs.c
+++ b/contrib/pageinspect/btreefuncs.c
@@ -49,7 +49,6 @@ PG_FUNCTION_INFO_V1(bt_page_stats_1_9);
 PG_FUNCTION_INFO_V1(bt_page_stats);
 PG_FUNCTION_INFO_V1(bt_multi_page_stats);
 
-#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
 #define IS_BTREE(r) ((r)->rd_rel->relam == BTREE_AM_OID)
 
 /* ------------------------------------------------
diff --git a/contrib/pageinspect/ginfuncs.c b/contrib/pageinspect/ginfuncs.c
index c9cf08872ac..dff77068804 100644
--- a/contrib/pageinspect/ginfuncs.c
+++ b/contrib/pageinspect/ginfuncs.c
@@ -30,7 +30,6 @@ PG_FUNCTION_INFO_V1(gin_entrypage_items);
 PG_FUNCTION_INFO_V1(gin_leafpage_items);
 PG_FUNCTION_INFO_V1(gin_datapage_items);
 
-#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
 #define IS_GIN(r) ((r)->rd_rel->relam == GIN_AM_OID)
 
 Datum
diff --git a/contrib/pageinspect/hashfuncs.c b/contrib/pageinspect/hashfuncs.c
index 7fc97d043ce..6a0d59befc1 100644
--- a/contrib/pageinspect/hashfuncs.c
+++ b/contrib/pageinspect/hashfuncs.c
@@ -28,7 +28,6 @@ PG_FUNCTION_INFO_V1(hash_page_items);
 PG_FUNCTION_INFO_V1(hash_bitmap_info);
 PG_FUNCTION_INFO_V1(hash_metapage_info);
 
-#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
 #define IS_HASH(r) ((r)->rd_rel->relam == HASH_AM_OID)
 
 /* ------------------------------------------------
diff --git a/contrib/pageinspect/pageinspect.h b/contrib/pageinspect/pageinspect.h
index b241fdc97b2..7e5d28eeb4d 100644
--- a/contrib/pageinspect/pageinspect.h
+++ b/contrib/pageinspect/pageinspect.h
@@ -24,6 +24,8 @@ enum pageinspect_version
 	PAGEINSPECT_V1_9,
 };
 
+#define IS_INDEX(r) ((r)->rd_rel->relkind == RELKIND_INDEX)
+
 /* in rawpage.c */
 extern Page get_page_from_raw(bytea *raw_page);
 
-- 
2.43.0