[PATCH] src/test/modules/dummy_index -- way to test reloptions from inside of access method

diff --git a/.gitignore b/.gitignore
index 794e35b..37331c2 100644
diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index dfd0956..742078e 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -7,6 +7,7 @@ include $(top_builddir)/src/Makefile.global
 SUBDIRS = \
 		  brin \
 		  commit_ts \
+		  dummy_index_am \
 		  dummy_seclabel \
 		  snapshot_too_old \
 		  test_bloomfilter \
diff --git a/src/test/modules/dummy_index_am/.gitignore b/src/test/modules/dummy_index_am/.gitignore
new file mode 100644
index 0000000..5dcb3ff
--- /dev/null
+++ b/src/test/modules/dummy_index_am/.gitignore
@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/
diff --git a/src/test/modules/dummy_index_am/Makefile b/src/test/modules/dummy_index_am/Makefile
new file mode 100644
index 0000000..695941b
--- /dev/null
+++ b/src/test/modules/dummy_index_am/Makefile
@@ -0,0 +1,21 @@
+# contrib/bloom/Makefile
+
+MODULE_big = dummy_index_am
+OBJS = dummy_index.o direloptions.o $(WIN32RES)
+
+EXTENSION = dummy_index_am
+DATA = dummy_index_am--1.0.sql
+PGFILEDESC = "dummy index access method - needed for all kinds of tests"
+
+REGRESS = reloptions
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/dummy_index_am
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/dummy_index_am/README b/src/test/modules/dummy_index_am/README
new file mode 100644
index 0000000..61f80d3
--- /dev/null
+++ b/src/test/modules/dummy_index_am/README
@@ -0,0 +1,45 @@
+Dummy index AM
+==============
+
+Dummy index, an index module for testing am-related internal calls that can't be
+properly tested inside production indexes, but better to be tested inside actual
+access method module.
+
+Guidelines:
+1. Keep this index as simple as as possible. It should not do any real indexing
+(unless you need it for your tests), if you need it make it as simple as
+possible;
+2. Keep all code related to feature you test inside id[name_of_a_feature].c
+file. dummy_index.c file should contain code that is needed for everyone, and
+make calls to feature-related code;
+3. Code related to your feature tests should be enabled and disabled by GUC
+variables. Create as many boolean GUC variables as you need and set them on so
+your test will know when it is time to do test output. Thus output from
+different features tests are not interfered;
+4. Add section to this README file that describes the general idea of what your
+tests do.
+
+Reloptions tests
+================
+
+Some relotions testing are done in regression tests. There we can check if new
+option value properly reaches pg_class, minimum/maximum checks, etc. But we
+can't check if option value successfully reached index internal code when we are
+dealing with production indexes. But  we can do it here in Dummy index.
+Here we check that values of reloptions properly reaches am-internals, and that
+all reloption-related code works as expected. Several GUC variables are defined
+to control test's output. do_test_reloptions turns on and off any
+reloptions-related output. You will also get some test output in the case when
+no relation options is set at all. do_test_reloption_int,
+do_test_reloption_real, do_test_reloption_bool and do_test_reloption_string
+allows to enable test output for int, real, boolean and string options.
+do_test_reloption_string2 enables test output for another string option. We need
+second string option, because a) string reloption implementation is a bit
+tricky, and it is better to check that second value works as well; b) better to
+check both cases: string option with validation function and without one, so we
+need two string options.
+
+
+Authors
+=======
+Nikolay Shaplov <dhyan@nataraj.su> (Dummy index core, reloptions tests)
diff --git a/src/test/modules/dummy_index_am/direloptions.c b/src/test/modules/dummy_index_am/direloptions.c
new file mode 100644
index 0000000..3c7cca5
--- /dev/null
+++ b/src/test/modules/dummy_index_am/direloptions.c
@@ -0,0 +1,219 @@
+/*-------------------------------------------------------------------------
+ *
+ *	direloptions.c
+ *		Functions and variables needed for reloptions tests.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	 src/test/modules/dummy_index_am/direloptions.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+#include "utils/rel.h"
+#include "access/reloptions.h"
+#include "utils/guc.h"
+
+#include "dummy_index.h"
+
+
+/* parse table for fillRelOptions */
+relopt_parse_elt di_relopt_tab[5];
+
+
+/* Kind of relation options for dummy index */
+relopt_kind di_relopt_kind;
+
+/* GUC variables */
+static bool do_test_reloptions = false;
+static bool do_test_reloption_int = false;
+static bool do_test_reloption_real = false;
+static bool do_test_reloption_bool = false;
+static bool do_test_reloption_string = false;
+static bool do_test_reloption_string2 = false;
+
+/*
+ * This function creates reloptions that would be used in reloptions tests
+ */
+void
+create_reloptions_table()
+{
+	di_relopt_kind = add_reloption_kind();
+
+	add_int_reloption(di_relopt_kind, "int_option",
+					  "Int option used for relotions test purposes",
+					  10, -10, 100);
+	di_relopt_tab[0].optname = "int_option";
+	di_relopt_tab[0].opttype = RELOPT_TYPE_INT;
+	di_relopt_tab[0].offset = offsetof(DummyIndexOptions, int_option);
+
+	add_real_reloption(di_relopt_kind, "real_option",
+					   "Real option used for relotions test purposes",
+					   3.1415, -10, 100);
+	di_relopt_tab[1].optname = "real_option";
+	di_relopt_tab[1].opttype = RELOPT_TYPE_REAL;
+	di_relopt_tab[1].offset = offsetof(DummyIndexOptions, real_option);
+
+
+	add_bool_reloption(di_relopt_kind, "bool_option",
+					   "Boolean option used for relotions test purposes",
+					   true);
+	di_relopt_tab[2].optname = "bool_option";
+	di_relopt_tab[2].opttype = RELOPT_TYPE_BOOL;
+	di_relopt_tab[2].offset = offsetof(DummyIndexOptions, bool_option);
+
+	add_string_reloption(di_relopt_kind, "string_option",
+						 "String option used for relotions test purposes",
+						 "DefaultValue", &validate_string_option);
+	di_relopt_tab[3].optname = "string_option";
+	di_relopt_tab[3].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[3].offset = offsetof(DummyIndexOptions, string_option_offset);
+
+	add_string_reloption(di_relopt_kind, "string_option2",
+					 "Second string option used for relotions test purposes",
+						 "SecondDefaultValue", &validate_string_option);
+	di_relopt_tab[4].optname = "string_option2";
+	di_relopt_tab[4].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[4].offset = offsetof(DummyIndexOptions, string_option2_offset);
+
+}
+
+/*
+ * This function creates GUC variables that allows to turn on and off test
+ * output for different relopntions
+ */
+void
+create_reloptions_test_GUC()
+{
+	DefineCustomBoolVariable("dummy_index.do_test_reloptions",
+						  "Set to true if you are going to test reloptions.",
+							 NULL,
+							 &do_test_reloptions,
+							 false,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+
+	DefineCustomBoolVariable("dummy_index.do_test_reloption_int",
+					   "Set to true if you are going to test int reloption.",
+							 NULL,
+							 &do_test_reloption_int,
+							 false,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+
+	DefineCustomBoolVariable("dummy_index.do_test_reloption_real",
+					  "Set to true if you are going to test real reloption.",
+							 NULL,
+							 &do_test_reloption_real,
+							 false,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+
+	DefineCustomBoolVariable("dummy_index.do_test_reloption_bool",
+				   "Set to true if you are going to test boolean reloption.",
+							 NULL,
+							 &do_test_reloption_bool,
+							 false,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+
+	DefineCustomBoolVariable("dummy_index.do_test_reloption_string",
+					"Set to true if you are going to test string reloption.",
+							 NULL,
+							 &do_test_reloption_string,
+							 false,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+	DefineCustomBoolVariable("dummy_index.do_test_reloption_string2",
+			 "Set to true if you are going to test second string reloption.",
+							 NULL,
+							 &do_test_reloption_string2,
+							 false,
+							 PGC_USERSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+}
+
+/*
+ * Function prints output for reloptions tests if GUC variables switches are
+ * properly set on.
+ */
+void
+print_reloptions_test_output(Relation index)
+{
+	if (do_test_reloptions)
+	{
+		if (!index->rd_options)
+		{
+			elog(WARNING, "No reloptions is set, default values will be chosen in module runtime");
+		}
+		else
+		{
+			DummyIndexOptions *opt;
+
+			opt = (DummyIndexOptions *) index->rd_options;
+			if (do_test_reloption_int)
+			{
+				elog(WARNING, "int_option = %d", opt->int_option);
+			}
+			if (do_test_reloption_real)
+			{
+				elog(WARNING, "real_option = %f", opt->real_option);
+			}
+			if (do_test_reloption_bool)
+			{
+				elog(WARNING, "bool_option = %d", opt->bool_option);
+			}
+			if (do_test_reloption_string)
+			{
+				char	   *str;
+
+				str = (char *) opt + opt->string_option_offset;
+				elog(WARNING, "string_option = '%s'", str);
+			}
+			if (do_test_reloption_string2)
+			{
+				char	   *str;
+
+				str = (char *) opt + opt->string_option2_offset;
+				elog(WARNING, "string_option2 = '%s'", str);
+			}
+		}
+	}
+}
+
+/*
+ * Validation function for string_option reloption
+ */
+void
+validate_string_option(const char *value)
+{
+	if (do_test_reloptions && do_test_reloption_string)
+	{
+		if (value)
+			elog(WARNING, "Validating string option '%s'", value);
+		else
+			elog(WARNING, "Validating string option with NULL value");
+	}
+	if (!value || *value == 'I')
+		elog(ERROR, "This seems to be invalid value. Please set valid value");
+}
diff --git a/src/test/modules/dummy_index_am/dummy_index.c b/src/test/modules/dummy_index_am/dummy_index.c
new file mode 100644
index 0000000..bd4c665
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index.c
@@ -0,0 +1,197 @@
+/*-------------------------------------------------------------------------
+ *
+ * dummy_index.c
+ *		Dummy index AM main file.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/test/modules/dummy_index_am/dummy_index.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/amapi.h"
+#include "catalog/index.h"
+#include "access/reloptions.h"
+#include "utils/guc.h"
+#include "dummy_index.h"
+
+
+PG_FUNCTION_INFO_V1(dihandler);
+PG_MODULE_MAGIC;
+
+void
+_PG_init(void)
+
+{
+	create_reloptions_table();
+	create_reloptions_test_GUC();
+}
+
+/*
+ * Dummy index handler function: return IndexAmRoutine with access method
+ * parameters and callbacks.
+ */
+Datum
+dihandler(PG_FUNCTION_ARGS)
+{
+	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
+
+	amroutine->amstrategies = 0;
+	amroutine->amsupport = 1;
+	amroutine->amcanorder = false;
+	amroutine->amcanorderbyop = false;
+	amroutine->amcanbackward = false;
+	amroutine->amcanunique = false;
+	amroutine->amcanmulticol = false;
+	amroutine->amoptionalkey = false;
+	amroutine->amsearcharray = false;
+	amroutine->amsearchnulls = false;
+	amroutine->amstorage = false;
+	amroutine->amclusterable = false;
+	amroutine->ampredlocks = false;
+	amroutine->amcanparallel = false;
+	amroutine->amcaninclude = false;
+	amroutine->amkeytype = InvalidOid;
+
+	amroutine->ambuild = dibuild;
+	amroutine->ambuildempty = dibuildempty;
+	amroutine->aminsert = diinsert;
+	amroutine->ambulkdelete = dibulkdelete;
+	amroutine->amvacuumcleanup = divacuumcleanup;
+	amroutine->amcanreturn = NULL;
+	amroutine->amcostestimate = dicostestimate;
+	amroutine->amoptions = dioptions;
+	amroutine->amproperty = NULL;
+	amroutine->amvalidate = divalidate;
+	amroutine->ambeginscan = dibeginscan;
+	amroutine->amrescan = direscan;
+	amroutine->amgettuple = NULL;
+	amroutine->amgetbitmap = NULL;
+	amroutine->amendscan = diendscan;
+	amroutine->ammarkpos = NULL;
+	amroutine->amrestrpos = NULL;
+	amroutine->amestimateparallelscan = NULL;
+	amroutine->aminitparallelscan = NULL;
+	amroutine->amparallelrescan = NULL;
+
+	PG_RETURN_POINTER(amroutine);
+}
+
+IndexBuildResult *
+dibuild(Relation heap, Relation index, IndexInfo *indexInfo)
+{
+	IndexBuildResult *result;
+
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
+
+	/* let's pretend that no tuples were scanned */
+	result->heap_tuples = 0;
+	/* and no index tuples were created (that is true) */
+	result->index_tuples = 0;
+
+	print_reloptions_test_output(index);
+
+	return result;
+}
+
+void
+dibuildempty(Relation index)
+{
+	/* Let's see what will happen if nothing is done here */
+	/* Add tests for reloptions here */
+}
+
+bool
+diinsert(Relation index, Datum *values, bool *isnull,
+		 ItemPointer ht_ctid, Relation heapRel,
+		 IndexUniqueCheck checkUnique,
+		 IndexInfo *indexInfo)
+{
+	/* This is Dummy Index we do nothing on insert :-) */
+	print_reloptions_test_output(index);
+	return false;
+
+}
+
+IndexBulkDeleteResult *
+dibulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
+			 IndexBulkDeleteCallback callback, void *callback_state)
+{
+	/*
+	 * Do not delete anything; Return NULL as we have nothing to pass to
+	 * amvacuumcleanup
+	 */
+	return NULL;
+}
+
+IndexBulkDeleteResult *
+divacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
+{
+	/* Index have not been modified, so it is absolutely right to return NULL */
+	return NULL;
+}
+
+void
+dicostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
+			   Cost *indexStartupCost, Cost *indexTotalCost,
+			   Selectivity *indexSelectivity, double *indexCorrelation,
+			   double *indexPages)
+{
+	/* Tell planner to never use this index! */
+	*indexStartupCost = 1.0e10; /* AKA disable_cost */
+	*indexTotalCost = 1.0e10;	/* AKA disable_cost */
+
+	/* Do not care about the rest */
+	*indexSelectivity = 1;
+	*indexCorrelation = 0;
+	*indexPages = 1;
+}
+
+bytea *
+dioptions(Datum reloptions, bool validate)
+{
+	relopt_value *options;
+	int			numoptions;
+	DummyIndexOptions *rdopts;
+
+	/* Parse the user-given reloptions */
+	options = parseRelOptions(reloptions, validate, di_relopt_kind, &numoptions);
+	rdopts = allocateReloptStruct(sizeof(DummyIndexOptions), options, numoptions);
+	fillRelOptions((void *) rdopts, sizeof(DummyIndexOptions), options, numoptions,
+				   validate, di_relopt_tab, lengthof(di_relopt_tab));
+
+	return (bytea *) rdopts;
+}
+
+bool
+divalidate(Oid opclassoid)
+{
+	/* Index does not really work so we are happy with any opclass */
+	return true;
+}
+
+IndexScanDesc
+dibeginscan(Relation r, int nkeys, int norderbys)
+{
+	IndexScanDesc scan;
+
+	/* Let's pretend we are doing something, just in case */
+	scan = RelationGetIndexScan(r, nkeys, norderbys);
+	return scan;
+}
+
+void
+direscan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
+		 ScanKey orderbys, int norderbys)
+{
+	/* Just do nothing */
+}
+
+void
+diendscan(IndexScanDesc scan)
+{
+	/* Do nothing */
+}
diff --git a/src/test/modules/dummy_index_am/dummy_index.h b/src/test/modules/dummy_index_am/dummy_index.h
new file mode 100644
index 0000000..fa6e405
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index.h
@@ -0,0 +1,66 @@
+/*-------------------------------------------------------------------------
+ *
+ * dummy_index.h
+ *	  Header for dummy_index_am index.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	 src/test/modules/dummy_index_am/dummy_index.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _DUMMY_INDEX_H_
+#define _DUMMY_INDEX_H_
+
+#include "nodes/pathnodes.h"
+
+/* Dummy index options */
+typedef struct DummyIndexOptions
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int			int_option;		/* for reloptions test purposes */
+	double		real_option;	/* for reloptions test purposes */
+	bool		bool_option;	/* for reloptions test purposes */
+	int			string_option_offset;	/* for reloptions test purposes */
+	int			string_option2_offset;	/* for reloptions test purposes */
+}	DummyIndexOptions;
+
+extern void _PG_init(void);
+
+/* index access method interface functions */
+extern bool divalidate(Oid opclassoid);
+extern bool diinsert(Relation index, Datum *values, bool *isnull,
+		 ItemPointer ht_ctid, Relation heapRel,
+		 IndexUniqueCheck checkUnique,
+		 struct IndexInfo *indexInfo);
+extern IndexScanDesc dibeginscan(Relation r, int nkeys, int norderbys);
+extern void direscan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
+		 ScanKey orderbys, int norderbys);
+extern void diendscan(IndexScanDesc scan);
+extern IndexBuildResult *dibuild(Relation heap, Relation index,
+		struct IndexInfo *indexInfo);
+extern void dibuildempty(Relation index);
+extern IndexBulkDeleteResult *dibulkdelete(IndexVacuumInfo *info,
+			 IndexBulkDeleteResult *stats, IndexBulkDeleteCallback callback,
+			 void *callback_state);
+extern IndexBulkDeleteResult *divacuumcleanup(IndexVacuumInfo *info,
+				IndexBulkDeleteResult *stats);
+extern bytea *dioptions(Datum reloptions, bool validate);
+extern void dicostestimate(PlannerInfo *root, IndexPath *path,
+			   double loop_count, Cost *indexStartupCost,
+			   Cost *indexTotalCost, Selectivity *indexSelectivity,
+			   double *indexCorrelation, double *indexPages);
+
+/* direoptions.c */
+/* Functions and variables needed for reloptions tests*/
+
+extern relopt_parse_elt di_relopt_tab[5];
+extern relopt_kind di_relopt_kind;
+
+extern void create_reloptions_table(void);
+extern void create_reloptions_test_GUC(void);
+extern void print_reloptions_test_output(Relation index);
+extern void validate_string_option(const char *value);
+
+#endif
diff --git a/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql b/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
new file mode 100644
index 0000000..8049c43
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
@@ -0,0 +1,20 @@
+/* src/test/modules/dummy_index/dummy_index_am--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION dummy_index_am" to load this file. \quit
+
+CREATE FUNCTION dihandler(internal)
+RETURNS index_am_handler
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+-- Access method
+CREATE ACCESS METHOD dummy_index_am TYPE INDEX HANDLER dihandler;
+COMMENT ON ACCESS METHOD dummy_index_am IS 'dummy index am is access method for test purposes';
+
+-- Opclasses
+
+CREATE OPERATOR CLASS int4_ops
+DEFAULT FOR TYPE int4 USING dummy_index_am AS
+	OPERATOR	1	=(int4, int4),
+	FUNCTION	1   hashint4(int4);
diff --git a/src/test/modules/dummy_index_am/dummy_index_am.control b/src/test/modules/dummy_index_am/dummy_index_am.control
new file mode 100644
index 0000000..93fb57b
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am.control
@@ -0,0 +1,5 @@
+# dummy_index extension
+comment = 'dummmy_index_am access method that does nothin and is used for test purposes'
+default_version = '1.0'
+module_pathname = '$libdir/dummy_index_am'
+relocatable = true
diff --git a/src/test/modules/dummy_index_am/expected/reloptions.out b/src/test/modules/dummy_index_am/expected/reloptions.out
new file mode 100644
index 0000000..f80b2fc
--- /dev/null
+++ b/src/test/modules/dummy_index_am/expected/reloptions.out
@@ -0,0 +1,97 @@
+CREATE EXTENSION dummy_index_am;
+SET dummy_index.do_test_reloptions to true;
+CREATE TABLE tst (i int4);
+-- Test reloptions behavior when no reloption is set
+CREATE INDEX test_idx ON tst USING dummy_index_am (i);
+WARNING:  No reloptions is set, default values will be chosen in module runtime
+DROP INDEX test_idx;
+-- Test behavior of int option (default and non default values)
+SET dummy_index.do_test_reloption_int to true;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (bool_option = false);
+WARNING:  int_option = 10
+DROP INDEX test_idx;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (int_option = 5);
+WARNING:  int_option = 5
+ALTER INDEX test_idx SET (int_option = 3);
+INSERT INTO tst VALUES(1);
+WARNING:  int_option = 3
+ALTER INDEX test_idx SET (bool_option = false);
+ALTER INDEX test_idx RESET (int_option);
+INSERT INTO tst VALUES(1);
+WARNING:  int_option = 10
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_int to false;
+-- Test behavior of real option (default and non default values)
+SET dummy_index.do_test_reloption_real to true;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (bool_option = false);
+WARNING:  real_option = 3.141500
+DROP INDEX test_idx;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (real_option = 5);
+WARNING:  real_option = 5.000000
+ALTER INDEX test_idx SET (real_option = 3);
+INSERT INTO tst VALUES(1);
+WARNING:  real_option = 3.000000
+ALTER INDEX test_idx SET (bool_option = false);
+ALTER INDEX test_idx RESET (real_option);
+INSERT INTO tst VALUES(1);
+WARNING:  real_option = 3.141500
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_real to false;
+-- Test behavior of bool option (default and non default values)
+SET dummy_index.do_test_reloption_bool to true;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (int_option = 5);
+WARNING:  bool_option = 1
+DROP INDEX test_idx;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (bool_option = false);
+WARNING:  bool_option = 0
+ALTER INDEX test_idx SET (bool_option = true);
+INSERT INTO tst VALUES(1);
+WARNING:  bool_option = 1
+ALTER INDEX test_idx SET (int_option = 5, bool_option = false);
+ALTER INDEX test_idx RESET (bool_option);
+INSERT INTO tst VALUES(1);
+WARNING:  bool_option = 1
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_bool to false;
+-- Test behavior of string option (default and non default values + validate
+-- function)
+SET dummy_index.do_test_reloption_string to true;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (int_option = 5);
+WARNING:  string_option = 'DefaultValue'
+DROP INDEX test_idx;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option =
+"Invalid_value");
+WARNING:  Validating string option 'Invalid_value'
+ERROR:  This seems to be invalid value. Please set valid value
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option =
+"Valid_value");
+WARNING:  Validating string option 'Valid_value'
+WARNING:  string_option = 'Valid_value'
+ALTER INDEX test_idx SET (string_option = "Valid_value_2", int_option = 5);
+WARNING:  Validating string option 'Valid_value_2'
+INSERT INTO tst VALUES(1);
+WARNING:  string_option = 'Valid_value_2'
+ALTER INDEX test_idx RESET (string_option);
+INSERT INTO tst VALUES(1);
+WARNING:  string_option = 'DefaultValue'
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_string to false;
+-- Test behavior of second string option
+-- Testing default and non default values + _no_ validate function)
+SET dummy_index.do_test_reloption_string2 to true;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option =
+"Something");
+WARNING:  string_option2 = 'SecondDefaultValue'
+DROP INDEX test_idx;
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option2 =
+"Some_value");
+WARNING:  string_option2 = 'Some_value'
+ALTER INDEX test_idx SET (string_option2 = "Valid_value_2", int_option = 5);
+INSERT INTO tst VALUES(1);
+WARNING:  string_option2 = 'Valid_value_2'
+ALTER INDEX test_idx RESET (string_option2);
+INSERT INTO tst VALUES(1);
+WARNING:  string_option2 = 'SecondDefaultValue'
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_string2 to false;
+SET dummy_index.do_test_reloptions to false;
diff --git a/src/test/modules/dummy_index_am/sql/reloptions.sql b/src/test/modules/dummy_index_am/sql/reloptions.sql
new file mode 100644
index 0000000..804a358
--- /dev/null
+++ b/src/test/modules/dummy_index_am/sql/reloptions.sql
@@ -0,0 +1,101 @@
+CREATE EXTENSION dummy_index_am;
+
+SET dummy_index.do_test_reloptions to true;
+
+CREATE TABLE tst (i int4);
+
+-- Test reloptions behavior when no reloption is set
+CREATE INDEX test_idx ON tst USING dummy_index_am (i);
+DROP INDEX test_idx;
+
+-- Test behavior of int option (default and non default values)
+SET dummy_index.do_test_reloption_int to true;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (bool_option = false);
+DROP INDEX test_idx;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (int_option = 5);
+
+ALTER INDEX test_idx SET (int_option = 3);
+INSERT INTO tst VALUES(1);
+ALTER INDEX test_idx SET (bool_option = false);
+ALTER INDEX test_idx RESET (int_option);
+INSERT INTO tst VALUES(1);
+
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_int to false;
+
+-- Test behavior of real option (default and non default values)
+SET dummy_index.do_test_reloption_real to true;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (bool_option = false);
+DROP INDEX test_idx;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (real_option = 5);
+
+ALTER INDEX test_idx SET (real_option = 3);
+INSERT INTO tst VALUES(1);
+ALTER INDEX test_idx SET (bool_option = false);
+ALTER INDEX test_idx RESET (real_option);
+INSERT INTO tst VALUES(1);
+
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_real to false;
+
+-- Test behavior of bool option (default and non default values)
+SET dummy_index.do_test_reloption_bool to true;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (int_option = 5);
+DROP INDEX test_idx;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (bool_option = false);
+
+ALTER INDEX test_idx SET (bool_option = true);
+INSERT INTO tst VALUES(1);
+ALTER INDEX test_idx SET (int_option = 5, bool_option = false);
+ALTER INDEX test_idx RESET (bool_option);
+INSERT INTO tst VALUES(1);
+
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_bool to false;
+
+-- Test behavior of string option (default and non default values + validate
+-- function)
+SET dummy_index.do_test_reloption_string to true;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (int_option = 5);
+DROP INDEX test_idx;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option =
+"Invalid_value");
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option =
+"Valid_value");
+
+ALTER INDEX test_idx SET (string_option = "Valid_value_2", int_option = 5);
+INSERT INTO tst VALUES(1);
+ALTER INDEX test_idx RESET (string_option);
+INSERT INTO tst VALUES(1);
+
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_string to false;
+
+-- Test behavior of second string option
+-- Testing default and non default values + _no_ validate function)
+SET dummy_index.do_test_reloption_string2 to true;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option =
+"Something");
+DROP INDEX test_idx;
+
+CREATE INDEX test_idx ON tst USING dummy_index_am (i) WITH (string_option2 =
+"Some_value");
+
+ALTER INDEX test_idx SET (string_option2 = "Valid_value_2", int_option = 5);
+INSERT INTO tst VALUES(1);
+ALTER INDEX test_idx RESET (string_option2);
+INSERT INTO tst VALUES(1);
+
+DROP INDEX test_idx;
+SET dummy_index.do_test_reloption_string2 to false;
+SET dummy_index.do_test_reloptions to false;

diff --git a/contrib/bloom/expected/bloom.out b/contrib/bloom/expected/bloom.out
index 5ab9e34f82..dae12a7d3e 100644
--- a/contrib/bloom/expected/bloom.out
+++ b/contrib/bloom/expected/bloom.out
@@ -5,6 +5,7 @@ CREATE TABLE tst (
 );
 INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
 CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
+ALTER INDEX bloomidx SET (length=80);
 SET enable_seqscan=on;
 SET enable_bitmapscan=off;
 SET enable_indexscan=off;
diff --git a/contrib/bloom/sql/bloom.sql b/contrib/bloom/sql/bloom.sql
index 32755f2b1a..4733e1e705 100644
--- a/contrib/bloom/sql/bloom.sql
+++ b/contrib/bloom/sql/bloom.sql
@@ -7,6 +7,7 @@ CREATE TABLE tst (
 
 INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
 CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
+ALTER INDEX bloomidx SET (length=80);
 
 SET enable_seqscan=on;
 SET enable_bitmapscan=off;
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 20f4ed3c38..b59e606771 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -659,6 +659,13 @@ allocate_reloption(bits32 kinds, int type, const char *name, const char *desc)
 	newoption->namelen = strlen(name);
 	newoption->type = type;
 
+	/*
+	 * Set the default lock mode for this option.  There is no actual way
+	 * for a module to enforce it when declaring a custom relation option,
+	 * so just use the highest level, which is safe for all cases.
+	 */
+	newoption->lockmode = AccessExclusiveLock;
+
 	MemoryContextSwitchTo(oldcxt);
 
 	return newoption;
diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index 0e4e53d63e..b2eaef3bff 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -7,6 +7,7 @@ include $(top_builddir)/src/Makefile.global
 SUBDIRS = \
 		  brin \
 		  commit_ts \
+		  dummy_index_am \
 		  dummy_seclabel \
 		  snapshot_too_old \
 		  test_bloomfilter \
diff --git a/src/test/modules/dummy_index_am/.gitignore b/src/test/modules/dummy_index_am/.gitignore
new file mode 100644
index 0000000000..5dcb3ff972
--- /dev/null
+++ b/src/test/modules/dummy_index_am/.gitignore
@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/
diff --git a/src/test/modules/dummy_index_am/Makefile b/src/test/modules/dummy_index_am/Makefile
new file mode 100644
index 0000000000..b7e09b1469
--- /dev/null
+++ b/src/test/modules/dummy_index_am/Makefile
@@ -0,0 +1,20 @@
+# src/test/modules/dummy_index_am/Makefile
+
+MODULES = dummy_index_am
+
+EXTENSION = dummy_index_am
+DATA = dummy_index_am--1.0.sql
+PGFILEDESC = "dummy_index_am - minimized index access method"
+
+REGRESS = reloptions
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/dummy_index_am
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/dummy_index_am/README b/src/test/modules/dummy_index_am/README
new file mode 100644
index 0000000000..5563d060ac
--- /dev/null
+++ b/src/test/modules/dummy_index_am/README
@@ -0,0 +1,11 @@
+Dummy Index AM
+==============
+
+Dummy index is an index module for testing any facility usable by an index
+access method, whose code is kept a maximum simple.
+
+This includes tests for all relation option types:
+- boolean
+- integer
+- real
+- strings
diff --git a/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql b/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
new file mode 100644
index 0000000000..005863de87
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
@@ -0,0 +1,19 @@
+/* src/test/modules/dummy_index_am/dummy_index_am--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION dummy_index_am" to load this file. \quit
+
+CREATE FUNCTION dihandler(internal)
+RETURNS index_am_handler
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+-- Access method
+CREATE ACCESS METHOD dummy_index_am TYPE INDEX HANDLER dihandler;
+COMMENT ON ACCESS METHOD dummy_index_am IS 'dummy index access method';
+
+-- Operator classes
+CREATE OPERATOR CLASS int4_ops
+DEFAULT FOR TYPE int4 USING dummy_index_am AS
+  OPERATOR 1 = (int4, int4),
+  FUNCTION 1 hashint4(int4);
diff --git a/src/test/modules/dummy_index_am/dummy_index_am.c b/src/test/modules/dummy_index_am/dummy_index_am.c
new file mode 100644
index 0000000000..0cee0f62a0
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am.c
@@ -0,0 +1,271 @@
+/*-------------------------------------------------------------------------
+ *
+ * dummy_index.c
+ *		Dummy index AM main file.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/test/modules/dummy_index_am/dummy_index.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/amapi.h"
+#include "access/reloptions.h"
+#include "catalog/index.h"
+#include "nodes/pathnodes.h"
+#include "utils/guc.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+void _PG_init(void);
+
+/* parse table for fillRelOptions */
+relopt_parse_elt di_relopt_tab[5];
+
+/* Kind of relation options for dummy index */
+relopt_kind di_relopt_kind;
+
+/* Dummy index options */
+typedef struct DummyIndexOptions
+{
+	int32       vl_len_;        /* varlena header (do not touch directly!) */
+	int         option_int;
+	double      option_real;
+	bool        option_bool;
+	char	   *option_string_val;
+	char	   *option_option_null;
+} DummyIndexOptions;
+
+/*
+ * Validation function for string relation options.
+ */
+static void
+validate_string_option(const char *value)
+{
+	ereport(NOTICE,
+			(errmsg("new option value for string parameter %s",
+					value ? value : "NULL")));
+}
+
+/*
+ * This function creates a full set of relation option types,
+ * with various patterns.
+ */
+static void
+create_reloptions_table(void)
+{
+	di_relopt_kind = add_reloption_kind();
+
+	add_int_reloption(di_relopt_kind, "option_int",
+					  "Integer option for dummy_index_am",
+					  10, -10, 100);
+	di_relopt_tab[0].optname = "option_int";
+	di_relopt_tab[0].opttype = RELOPT_TYPE_INT;
+	di_relopt_tab[0].offset = offsetof(DummyIndexOptions, option_int);
+
+	add_real_reloption(di_relopt_kind, "option_real",
+					   "Real option for dummy_index_am",
+					   3.1415, -10, 100);
+	di_relopt_tab[1].optname = "option_real";
+	di_relopt_tab[1].opttype = RELOPT_TYPE_REAL;
+	di_relopt_tab[1].offset = offsetof(DummyIndexOptions, option_real);
+
+	add_bool_reloption(di_relopt_kind, "option_bool",
+					   "Boolean option for dummy_index_am",
+					   true);
+	di_relopt_tab[2].optname = "option_bool";
+	di_relopt_tab[2].opttype = RELOPT_TYPE_BOOL;
+	di_relopt_tab[2].offset = offsetof(DummyIndexOptions, option_bool);
+
+	add_string_reloption(di_relopt_kind, "option_string_val",
+						 "String option for dummy_index_am with non-NULL default",
+						 "DefaultValue", &validate_string_option);
+	di_relopt_tab[3].optname = "option_string_val";
+	di_relopt_tab[3].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[3].offset = offsetof(DummyIndexOptions, option_string_val);
+
+	/*
+	 * String option for dummy_index_am with NULL default, and without
+	 * description.
+	 */
+	add_string_reloption(di_relopt_kind, "option_string_null",
+						 NULL,	/* description */
+						 NULL, &validate_string_option);
+	di_relopt_tab[4].optname = "option_string_null";
+	di_relopt_tab[4].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[4].offset = offsetof(DummyIndexOptions, option_option_null);
+}
+
+
+PG_FUNCTION_INFO_V1(dihandler);
+
+static IndexBuildResult *
+dibuild(Relation heap, Relation index, IndexInfo *indexInfo)
+{
+	IndexBuildResult *result;
+
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
+
+	/* let's pretend that no tuples were scanned */
+	result->heap_tuples = 0;
+	/* and no index tuples were created (that is true) */
+	result->index_tuples = 0;
+
+	return result;
+}
+
+static void
+dibuildempty(Relation index)
+{
+	/* No need to build an init fork for a dummy index */
+}
+
+static bool
+diinsert(Relation index, Datum *values, bool *isnull,
+		 ItemPointer ht_ctid, Relation heapRel,
+		 IndexUniqueCheck checkUnique,
+		 IndexInfo *indexInfo)
+{
+	/* nothing to do */
+	return false;
+}
+
+static IndexBulkDeleteResult *
+dibulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
+			 IndexBulkDeleteCallback callback, void *callback_state)
+{
+	/*
+	 * There is nothing to delete.  Return NULL as there is nothing to
+	 * pass to amvacuumcleanup.
+	 */
+	return NULL;
+}
+
+static IndexBulkDeleteResult *
+divacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
+{
+	/* Index has not been modified, so returning NULL is fine */
+	return NULL;
+}
+
+static void
+dicostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
+			   Cost *indexStartupCost, Cost *indexTotalCost,
+			   Selectivity *indexSelectivity, double *indexCorrelation,
+			   double *indexPages)
+{
+	/* Tell planner to never use this index! */
+	*indexStartupCost = 1.0e10; /* AKA disable_cost */
+	*indexTotalCost = 1.0e10;	/* AKA disable_cost */
+
+	/* Do not care about the rest */
+	*indexSelectivity = 1;
+	*indexCorrelation = 0;
+	*indexPages = 1;
+}
+
+static bytea *
+dioptions(Datum reloptions, bool validate)
+{
+	relopt_value *options;
+	int			numoptions;
+	DummyIndexOptions *rdopts;
+
+	/* Parse the user-given reloptions */
+	options = parseRelOptions(reloptions, validate, di_relopt_kind, &numoptions);
+	rdopts = allocateReloptStruct(sizeof(DummyIndexOptions), options, numoptions);
+	fillRelOptions((void *) rdopts, sizeof(DummyIndexOptions), options, numoptions,
+				   validate, di_relopt_tab, lengthof(di_relopt_tab));
+
+	return (bytea *) rdopts;
+}
+
+static bool
+divalidate(Oid opclassoid)
+{
+	/* Index is dummy so we are happy with any opclass */
+	return true;
+}
+
+static IndexScanDesc
+dibeginscan(Relation r, int nkeys, int norderbys)
+{
+	IndexScanDesc scan;
+
+	/* Let's pretend we are doing something */
+	scan = RelationGetIndexScan(r, nkeys, norderbys);
+	return scan;
+}
+
+static void
+direscan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
+		 ScanKey orderbys, int norderbys)
+{
+	/* nothing to do */
+}
+
+static void
+diendscan(IndexScanDesc scan)
+{
+	/* nothing to do */
+}
+
+/*
+ * Dummy index handler function: return IndexAmRoutine with access method
+ * parameters and callbacks.
+ */
+Datum
+dihandler(PG_FUNCTION_ARGS)
+{
+	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
+
+	amroutine->amstrategies = 0;
+	amroutine->amsupport = 1;
+	amroutine->amcanorder = false;
+	amroutine->amcanorderbyop = false;
+	amroutine->amcanbackward = false;
+	amroutine->amcanunique = false;
+	amroutine->amcanmulticol = false;
+	amroutine->amoptionalkey = false;
+	amroutine->amsearcharray = false;
+	amroutine->amsearchnulls = false;
+	amroutine->amstorage = false;
+	amroutine->amclusterable = false;
+	amroutine->ampredlocks = false;
+	amroutine->amcanparallel = false;
+	amroutine->amcaninclude = false;
+	amroutine->amkeytype = InvalidOid;
+
+	amroutine->ambuild = dibuild;
+	amroutine->ambuildempty = dibuildempty;
+	amroutine->aminsert = diinsert;
+	amroutine->ambulkdelete = dibulkdelete;
+	amroutine->amvacuumcleanup = divacuumcleanup;
+	amroutine->amcanreturn = NULL;
+	amroutine->amcostestimate = dicostestimate;
+	amroutine->amoptions = dioptions;
+	amroutine->amproperty = NULL;
+	amroutine->amvalidate = divalidate;
+	amroutine->ambeginscan = dibeginscan;
+	amroutine->amrescan = direscan;
+	amroutine->amgettuple = NULL;
+	amroutine->amgetbitmap = NULL;
+	amroutine->amendscan = diendscan;
+	amroutine->ammarkpos = NULL;
+	amroutine->amrestrpos = NULL;
+	amroutine->amestimateparallelscan = NULL;
+	amroutine->aminitparallelscan = NULL;
+	amroutine->amparallelrescan = NULL;
+
+	PG_RETURN_POINTER(amroutine);
+}
+
+void
+_PG_init(void)
+{
+	create_reloptions_table();
+}
diff --git a/src/test/modules/dummy_index_am/dummy_index_am.control b/src/test/modules/dummy_index_am/dummy_index_am.control
new file mode 100644
index 0000000000..7ea62a0c1c
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am.control
@@ -0,0 +1,5 @@
+# dummy_index extension
+comment = 'dummy_index_am - minimized index access method'
+default_version = '1.0'
+module_pathname = '$libdir/dummy_index_am'
+relocatable = true
diff --git a/src/test/modules/dummy_index_am/expected/reloptions.out b/src/test/modules/dummy_index_am/expected/reloptions.out
new file mode 100644
index 0000000000..04a120a0e0
--- /dev/null
+++ b/src/test/modules/dummy_index_am/expected/reloptions.out
@@ -0,0 +1,77 @@
+-- Tests for relation options
+CREATE EXTENSION dummy_index_am;
+CREATE TABLE dummy_test_tab (i int4);
+-- Test with default values.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+ unnest 
+--------
+(0 rows)
+
+DROP INDEX dummy_test_idx;
+-- Test with full set of options.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i) WITH (
+  option_bool = false,
+  option_int = 5,
+  option_real = 3.1,
+  option_string_val = NULL,
+  option_string_null = 'val');
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+         unnest         
+------------------------
+ option_bool=false
+ option_int=5
+ option_real=3.1
+ option_string_val=null
+ option_string_null=val
+(5 rows)
+
+-- ALTER INDEX .. SET
+ALTER INDEX dummy_test_idx SET (option_int = 10);
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+ALTER INDEX dummy_test_idx SET (option_bool = true);
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+ALTER INDEX dummy_test_idx SET (option_real = 3.2);
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+ALTER INDEX dummy_test_idx SET (option_string_val = 'val2');
+NOTICE:  new option value for string parameter val
+NOTICE:  new option value for string parameter val2
+ALTER INDEX dummy_test_idx SET (option_string_null = NULL);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+         unnest          
+-------------------------
+ option_int=10
+ option_bool=true
+ option_real=3.2
+ option_string_val=val2
+ option_string_null=null
+(5 rows)
+
+-- ALTER INDEX .. RESET
+ALTER INDEX dummy_test_idx RESET (option_int);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_bool);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_real);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_string_val);
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_string_null);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+ unnest 
+--------
+(0 rows)
+
+DROP INDEX dummy_test_idx;
diff --git a/src/test/modules/dummy_index_am/sql/reloptions.sql b/src/test/modules/dummy_index_am/sql/reloptions.sql
new file mode 100644
index 0000000000..10ca1a6d03
--- /dev/null
+++ b/src/test/modules/dummy_index_am/sql/reloptions.sql
@@ -0,0 +1,38 @@
+-- Tests for relation options
+CREATE EXTENSION dummy_index_am;
+
+CREATE TABLE dummy_test_tab (i int4);
+
+-- Test with default values.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+DROP INDEX dummy_test_idx;
+
+-- Test with full set of options.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i) WITH (
+  option_bool = false,
+  option_int = 5,
+  option_real = 3.1,
+  option_string_val = NULL,
+  option_string_null = 'val');
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+
+-- ALTER INDEX .. SET
+ALTER INDEX dummy_test_idx SET (option_int = 10);
+ALTER INDEX dummy_test_idx SET (option_bool = true);
+ALTER INDEX dummy_test_idx SET (option_real = 3.2);
+ALTER INDEX dummy_test_idx SET (option_string_val = 'val2');
+ALTER INDEX dummy_test_idx SET (option_string_null = NULL);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+
+-- ALTER INDEX .. RESET
+ALTER INDEX dummy_test_idx RESET (option_int);
+ALTER INDEX dummy_test_idx RESET (option_bool);
+ALTER INDEX dummy_test_idx RESET (option_real);
+ALTER INDEX dummy_test_idx RESET (option_string_val);
+ALTER INDEX dummy_test_idx RESET (option_string_null);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+
+DROP INDEX dummy_test_idx;

From c0c2f75ae0b4fa3e6959a1157d400e316f40ada0 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 23 Sep 2019 15:20:37 +0900
Subject: [PATCH v2 1/3] Fix failure with lock mode used for custom relation
 options

Relation options can use a custom lock mode since 47167b7, which has
lowered the lock available for some autovacuum parameters, however it
forgot to consider custom relation options.  This causes failures with
ALTER TABLE SET when changing a custom relation option, as its lock is
not defined.  The existing APIs to define a custom reloption does not
allow to define a custom lock mode, so enforce its initialization to
AccessExclusiveMode which is safe enough in all cases.  An upcoming
patch will extend the existing APIs to allow a custom lock mode to be
defined.

The problem can be reproduced with bloom indexes, so add a test there.

Reported-by: Nikolay Sharplov
Analyzed-by: Thomas Munro, Michael Paquier
Author: Michael Paquier
Reviewed-by: Kuntal Ghosh
Discussion: https://postgr.es/m/20190920013831.GD1844@paquier.xyz
Backpatch-through: 9.6
---
 contrib/bloom/expected/bloom.out       | 1 +
 contrib/bloom/sql/bloom.sql            | 1 +
 src/backend/access/common/reloptions.c | 7 +++++++
 3 files changed, 9 insertions(+)

diff --git a/contrib/bloom/expected/bloom.out b/contrib/bloom/expected/bloom.out
index 5ab9e34f82..dae12a7d3e 100644
--- a/contrib/bloom/expected/bloom.out
+++ b/contrib/bloom/expected/bloom.out
@@ -5,6 +5,7 @@ CREATE TABLE tst (
 );
 INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
 CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
+ALTER INDEX bloomidx SET (length=80);
 SET enable_seqscan=on;
 SET enable_bitmapscan=off;
 SET enable_indexscan=off;
diff --git a/contrib/bloom/sql/bloom.sql b/contrib/bloom/sql/bloom.sql
index 32755f2b1a..4733e1e705 100644
--- a/contrib/bloom/sql/bloom.sql
+++ b/contrib/bloom/sql/bloom.sql
@@ -7,6 +7,7 @@ CREATE TABLE tst (
 
 INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
 CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
+ALTER INDEX bloomidx SET (length=80);
 
 SET enable_seqscan=on;
 SET enable_bitmapscan=off;
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 20f4ed3c38..b59e606771 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -659,6 +659,13 @@ allocate_reloption(bits32 kinds, int type, const char *name, const char *desc)
 	newoption->namelen = strlen(name);
 	newoption->type = type;
 
+	/*
+	 * Set the default lock mode for this option.  There is no actual way
+	 * for a module to enforce it when declaring a custom relation option,
+	 * so just use the highest level, which is safe for all cases.
+	 */
+	newoption->lockmode = AccessExclusiveLock;
+
 	MemoryContextSwitchTo(oldcxt);
 
 	return newoption;
-- 
2.23.0

From c495f03450b6c4727b3d2f44b3509916f0ee73ae Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 23 Sep 2019 15:28:02 +0900
Subject: [PATCH v2 2/3] Allow definition of lock mode for custom reloptions

Relation options can define a lock mode other than AccessExclusiveMode
since 47167b7, but modules defining custom relation options did not
really have a way to enforce that.  Correct that by extending the
current API set so as modules can define a custom lock mode.

Author: Michael Paquier
Reviewed-by: Kuntal Ghosh
Discussion: https://postgr.es/m/20190920013831.GD1844@paquier.xyz
---
 contrib/bloom/blutils.c                |  6 ++++--
 src/backend/access/common/reloptions.c | 28 +++++++++++---------------
 src/include/access/reloptions.h        | 11 ++++++----
 3 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index cc1670934f..dbb24cb5b2 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -60,7 +60,8 @@ _PG_init(void)
 	/* Option for length of signature */
 	add_int_reloption(bl_relopt_kind, "length",
 					  "Length of signature in bits",
-					  DEFAULT_BLOOM_LENGTH, 1, MAX_BLOOM_LENGTH);
+					  DEFAULT_BLOOM_LENGTH, 1, MAX_BLOOM_LENGTH,
+					  AccessExclusiveLock);
 	bl_relopt_tab[0].optname = "length";
 	bl_relopt_tab[0].opttype = RELOPT_TYPE_INT;
 	bl_relopt_tab[0].offset = offsetof(BloomOptions, bloomLength);
@@ -71,7 +72,8 @@ _PG_init(void)
 		snprintf(buf, sizeof(buf), "col%d", i + 1);
 		add_int_reloption(bl_relopt_kind, buf,
 						  "Number of bits generated for each index column",
-						  DEFAULT_BLOOM_BITS, 1, MAX_BLOOM_BITS);
+						  DEFAULT_BLOOM_BITS, 1, MAX_BLOOM_BITS,
+						  AccessExclusiveLock);
 		bl_relopt_tab[i + 1].optname = MemoryContextStrdup(TopMemoryContext,
 														   buf);
 		bl_relopt_tab[i + 1].opttype = RELOPT_TYPE_INT;
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index b59e606771..3b8517efea 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -621,7 +621,8 @@ add_reloption(relopt_gen *newoption)
  *		(for types other than string)
  */
 static relopt_gen *
-allocate_reloption(bits32 kinds, int type, const char *name, const char *desc)
+allocate_reloption(bits32 kinds, int type, const char *name, const char *desc,
+				   LOCKMODE lockmode)
 {
 	MemoryContext oldcxt;
 	size_t		size;
@@ -658,13 +659,7 @@ allocate_reloption(bits32 kinds, int type, const char *name, const char *desc)
 	newoption->kinds = kinds;
 	newoption->namelen = strlen(name);
 	newoption->type = type;
-
-	/*
-	 * Set the default lock mode for this option.  There is no actual way
-	 * for a module to enforce it when declaring a custom relation option,
-	 * so just use the highest level, which is safe for all cases.
-	 */
-	newoption->lockmode = AccessExclusiveLock;
+	newoption->lockmode = lockmode;
 
 	MemoryContextSwitchTo(oldcxt);
 
@@ -676,12 +671,13 @@ allocate_reloption(bits32 kinds, int type, const char *name, const char *desc)
  *		Add a new boolean reloption
  */
 void
-add_bool_reloption(bits32 kinds, const char *name, const char *desc, bool default_val)
+add_bool_reloption(bits32 kinds, const char *name, const char *desc,
+				   bool default_val, LOCKMODE lockmode)
 {
 	relopt_bool *newoption;
 
 	newoption = (relopt_bool *) allocate_reloption(kinds, RELOPT_TYPE_BOOL,
-												   name, desc);
+												   name, desc, lockmode);
 	newoption->default_val = default_val;
 
 	add_reloption((relopt_gen *) newoption);
@@ -693,12 +689,12 @@ add_bool_reloption(bits32 kinds, const char *name, const char *desc, bool defaul
  */
 void
 add_int_reloption(bits32 kinds, const char *name, const char *desc, int default_val,
-				  int min_val, int max_val)
+				  int min_val, int max_val, LOCKMODE lockmode)
 {
 	relopt_int *newoption;
 
 	newoption = (relopt_int *) allocate_reloption(kinds, RELOPT_TYPE_INT,
-												  name, desc);
+												  name, desc, lockmode);
 	newoption->default_val = default_val;
 	newoption->min = min_val;
 	newoption->max = max_val;
@@ -712,12 +708,12 @@ add_int_reloption(bits32 kinds, const char *name, const char *desc, int default_
  */
 void
 add_real_reloption(bits32 kinds, const char *name, const char *desc, double default_val,
-				   double min_val, double max_val)
+				   double min_val, double max_val, LOCKMODE lockmode)
 {
 	relopt_real *newoption;
 
 	newoption = (relopt_real *) allocate_reloption(kinds, RELOPT_TYPE_REAL,
-												   name, desc);
+												   name, desc, lockmode);
 	newoption->default_val = default_val;
 	newoption->min = min_val;
 	newoption->max = max_val;
@@ -736,7 +732,7 @@ add_real_reloption(bits32 kinds, const char *name, const char *desc, double defa
  */
 void
 add_string_reloption(bits32 kinds, const char *name, const char *desc, const char *default_val,
-					 validate_string_relopt validator)
+					 validate_string_relopt validator, LOCKMODE lockmode)
 {
 	relopt_string *newoption;
 
@@ -745,7 +741,7 @@ add_string_reloption(bits32 kinds, const char *name, const char *desc, const cha
 		(validator) (default_val);
 
 	newoption = (relopt_string *) allocate_reloption(kinds, RELOPT_TYPE_STRING,
-													 name, desc);
+													 name, desc, lockmode);
 	newoption->validate_cb = validator;
 	if (default_val)
 	{
diff --git a/src/include/access/reloptions.h b/src/include/access/reloptions.h
index 6d392e4d5a..4b82c6370a 100644
--- a/src/include/access/reloptions.h
+++ b/src/include/access/reloptions.h
@@ -247,13 +247,16 @@ typedef struct
 
 extern relopt_kind add_reloption_kind(void);
 extern void add_bool_reloption(bits32 kinds, const char *name, const char *desc,
-							   bool default_val);
+							   bool default_val, LOCKMODE lockmode);
 extern void add_int_reloption(bits32 kinds, const char *name, const char *desc,
-							  int default_val, int min_val, int max_val);
+							  int default_val, int min_val, int max_val,
+							  LOCKMODE lockmode);
 extern void add_real_reloption(bits32 kinds, const char *name, const char *desc,
-							   double default_val, double min_val, double max_val);
+							   double default_val, double min_val, double max_val,
+							   LOCKMODE lockmode);
 extern void add_string_reloption(bits32 kinds, const char *name, const char *desc,
-								 const char *default_val, validate_string_relopt validator);
+								 const char *default_val, validate_string_relopt validator,
+								 LOCKMODE lockmode);
 
 extern Datum transformRelOptions(Datum oldOptions, List *defList,
 								 const char *namspace, char *validnsps[],
-- 
2.23.0

From 2de282f4371786772bfa6bd7a4079e3d3ecadbba Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Tue, 24 Sep 2019 11:37:19 +0900
Subject: [PATCH v2 3/3] Add dummy_index_am to src/test/modules/

This includes for now more tests dedicated to reloptions, bringing the
coverage of this code close to 100%, and the module could be used for
other purposes, like a base template for an index AM implementation.

Author: Nikolay Sharplov
Reviewed-by: Dent John, Michael Paquier
Discussion: https://postgr.es/m/17071942.m9zZutALE6@x200m
---
 src/test/modules/Makefile                     |   1 +
 src/test/modules/dummy_index_am/.gitignore    |   3 +
 src/test/modules/dummy_index_am/Makefile      |  20 ++
 src/test/modules/dummy_index_am/README        |  11 +
 .../dummy_index_am/dummy_index_am--1.0.sql    |  19 ++
 .../modules/dummy_index_am/dummy_index_am.c   | 309 ++++++++++++++++++
 .../dummy_index_am/dummy_index_am.control     |   5 +
 .../dummy_index_am/expected/reloptions.out    |  77 +++++
 .../modules/dummy_index_am/sql/reloptions.sql |  38 +++
 9 files changed, 483 insertions(+)
 create mode 100644 src/test/modules/dummy_index_am/.gitignore
 create mode 100644 src/test/modules/dummy_index_am/Makefile
 create mode 100644 src/test/modules/dummy_index_am/README
 create mode 100644 src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
 create mode 100644 src/test/modules/dummy_index_am/dummy_index_am.c
 create mode 100644 src/test/modules/dummy_index_am/dummy_index_am.control
 create mode 100644 src/test/modules/dummy_index_am/expected/reloptions.out
 create mode 100644 src/test/modules/dummy_index_am/sql/reloptions.sql

diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index 0e4e53d63e..b2eaef3bff 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -7,6 +7,7 @@ include $(top_builddir)/src/Makefile.global
 SUBDIRS = \
 		  brin \
 		  commit_ts \
+		  dummy_index_am \
 		  dummy_seclabel \
 		  snapshot_too_old \
 		  test_bloomfilter \
diff --git a/src/test/modules/dummy_index_am/.gitignore b/src/test/modules/dummy_index_am/.gitignore
new file mode 100644
index 0000000000..44d119cfcc
--- /dev/null
+++ b/src/test/modules/dummy_index_am/.gitignore
@@ -0,0 +1,3 @@
+# Generated subdirectories
+/log/
+/results/
diff --git a/src/test/modules/dummy_index_am/Makefile b/src/test/modules/dummy_index_am/Makefile
new file mode 100644
index 0000000000..aaf544a385
--- /dev/null
+++ b/src/test/modules/dummy_index_am/Makefile
@@ -0,0 +1,20 @@
+# src/test/modules/dummy_index_am/Makefile
+
+MODULES = dummy_index_am
+
+EXTENSION = dummy_index_am
+DATA = dummy_index_am--1.0.sql
+PGFILEDESC = "dummy_index_am - index access method template"
+
+REGRESS = reloptions
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/dummy_index_am
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/dummy_index_am/README b/src/test/modules/dummy_index_am/README
new file mode 100644
index 0000000000..7bcdec56f3
--- /dev/null
+++ b/src/test/modules/dummy_index_am/README
@@ -0,0 +1,11 @@
+Dummy Index AM
+==============
+
+Dummy index AM is a module for testing any facility usable by an index
+access method, whose code is kept a maximum simple.
+
+This includes tests for all relation option types:
+- boolean
+- integer
+- real
+- strings (with and without NULL as default)
diff --git a/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql b/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
new file mode 100644
index 0000000000..005863de87
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am--1.0.sql
@@ -0,0 +1,19 @@
+/* src/test/modules/dummy_index_am/dummy_index_am--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION dummy_index_am" to load this file. \quit
+
+CREATE FUNCTION dihandler(internal)
+RETURNS index_am_handler
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
+-- Access method
+CREATE ACCESS METHOD dummy_index_am TYPE INDEX HANDLER dihandler;
+COMMENT ON ACCESS METHOD dummy_index_am IS 'dummy index access method';
+
+-- Operator classes
+CREATE OPERATOR CLASS int4_ops
+DEFAULT FOR TYPE int4 USING dummy_index_am AS
+  OPERATOR 1 = (int4, int4),
+  FUNCTION 1 hashint4(int4);
diff --git a/src/test/modules/dummy_index_am/dummy_index_am.c b/src/test/modules/dummy_index_am/dummy_index_am.c
new file mode 100644
index 0000000000..1211907e1d
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am.c
@@ -0,0 +1,309 @@
+/*-------------------------------------------------------------------------
+ *
+ * dummy_index_am.c
+ *		Index AM template main file.
+ *
+ * Copyright (c) 2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/test/modules/dummy_index_am/dummy_index_am.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/amapi.h"
+#include "access/reloptions.h"
+#include "catalog/index.h"
+#include "nodes/pathnodes.h"
+#include "utils/guc.h"
+#include "utils/rel.h"
+
+PG_MODULE_MAGIC;
+
+void		_PG_init(void);
+
+/* parse table for fillRelOptions */
+relopt_parse_elt di_relopt_tab[5];
+
+/* Kind of relation options for dummy index */
+relopt_kind di_relopt_kind;
+
+/* Dummy index options */
+typedef struct DummyIndexOptions
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int			option_int;
+	double		option_real;
+	bool		option_bool;
+	char	   *option_string_val;
+	char	   *option_option_null;
+} DummyIndexOptions;
+
+/* Handler for index AM */
+PG_FUNCTION_INFO_V1(dihandler);
+
+/*
+ * Validation function for string relation options.
+ */
+static void
+validate_string_option(const char *value)
+{
+	ereport(NOTICE,
+			(errmsg("new option value for string parameter %s",
+					value ? value : "NULL")));
+}
+
+/*
+ * This function creates a full set of relation option types,
+ * with various patterns.
+ */
+static void
+create_reloptions_table(void)
+{
+	di_relopt_kind = add_reloption_kind();
+
+	add_int_reloption(di_relopt_kind, "option_int",
+					  "Integer option for dummy_index_am",
+					  10, -10, 100, AccessExclusiveLock);
+	di_relopt_tab[0].optname = "option_int";
+	di_relopt_tab[0].opttype = RELOPT_TYPE_INT;
+	di_relopt_tab[0].offset = offsetof(DummyIndexOptions, option_int);
+
+	add_real_reloption(di_relopt_kind, "option_real",
+					   "Real option for dummy_index_am",
+					   3.1415, -10, 100, AccessExclusiveLock);
+	di_relopt_tab[1].optname = "option_real";
+	di_relopt_tab[1].opttype = RELOPT_TYPE_REAL;
+	di_relopt_tab[1].offset = offsetof(DummyIndexOptions, option_real);
+
+	add_bool_reloption(di_relopt_kind, "option_bool",
+					   "Boolean option for dummy_index_am",
+					   true, AccessExclusiveLock);
+	di_relopt_tab[2].optname = "option_bool";
+	di_relopt_tab[2].opttype = RELOPT_TYPE_BOOL;
+	di_relopt_tab[2].offset = offsetof(DummyIndexOptions, option_bool);
+
+	add_string_reloption(di_relopt_kind, "option_string_val",
+						 "String option for dummy_index_am with non-NULL default",
+						 "DefaultValue", &validate_string_option,
+						 AccessExclusiveLock);
+	di_relopt_tab[3].optname = "option_string_val";
+	di_relopt_tab[3].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[3].offset = offsetof(DummyIndexOptions, option_string_val);
+
+	/*
+	 * String option for dummy_index_am with NULL default, and without
+	 * description.
+	 */
+	add_string_reloption(di_relopt_kind, "option_string_null",
+						 NULL,	/* description */
+						 NULL, &validate_string_option,
+						 AccessExclusiveLock);
+	di_relopt_tab[4].optname = "option_string_null";
+	di_relopt_tab[4].opttype = RELOPT_TYPE_STRING;
+	di_relopt_tab[4].offset = offsetof(DummyIndexOptions, option_option_null);
+}
+
+
+/*
+ * Build a new index.
+ */
+static IndexBuildResult *
+dibuild(Relation heap, Relation index, IndexInfo *indexInfo)
+{
+	IndexBuildResult *result;
+
+	result = (IndexBuildResult *) palloc(sizeof(IndexBuildResult));
+
+	/* let's pretend that no tuples were scanned */
+	result->heap_tuples = 0;
+	/* and no index tuples were created (that is true) */
+	result->index_tuples = 0;
+
+	return result;
+}
+
+/*
+ * Build an empty index for the initialiation fork.
+ */
+static void
+dibuildempty(Relation index)
+{
+	/* No need to build an init fork for a dummy index */
+}
+
+/*
+ * Insert new tuple to index AM.
+ */
+static bool
+diinsert(Relation index, Datum *values, bool *isnull,
+		 ItemPointer ht_ctid, Relation heapRel,
+		 IndexUniqueCheck checkUnique,
+		 IndexInfo *indexInfo)
+{
+	/* nothing to do */
+	return false;
+}
+
+/*
+ * Bulk deletion of all index entries pointing to a set of table tuples.
+ */
+static IndexBulkDeleteResult *
+dibulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
+			 IndexBulkDeleteCallback callback, void *callback_state)
+{
+	/*
+	 * There is nothing to delete.  Return NULL as there is nothing to pass to
+	 * amvacuumcleanup.
+	 */
+	return NULL;
+}
+
+/*
+ * Post-VACUUM cleanup for index AM.
+ */
+static IndexBulkDeleteResult *
+divacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
+{
+	/* Index has not been modified, so returning NULL is fine */
+	return NULL;
+}
+
+/*
+ * Estimate cost of index AM.
+ */
+static void
+dicostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
+			   Cost *indexStartupCost, Cost *indexTotalCost,
+			   Selectivity *indexSelectivity, double *indexCorrelation,
+			   double *indexPages)
+{
+	/* Tell planner to never use this index! */
+	*indexStartupCost = 1.0e10;
+	*indexTotalCost = 1.0e10;
+
+	/* Do not care about the rest */
+	*indexSelectivity = 1;
+	*indexCorrelation = 0;
+	*indexPages = 1;
+}
+
+/*
+ * Parse relation options for index AM, returning a DummyIndexOptions
+ * structure filled with option values.
+ */
+static bytea *
+dioptions(Datum reloptions, bool validate)
+{
+	relopt_value *options;
+	int			numoptions;
+	DummyIndexOptions *rdopts;
+
+	/* Parse the user-given reloptions */
+	options = parseRelOptions(reloptions, validate, di_relopt_kind, &numoptions);
+	rdopts = allocateReloptStruct(sizeof(DummyIndexOptions), options, numoptions);
+	fillRelOptions((void *) rdopts, sizeof(DummyIndexOptions), options, numoptions,
+				   validate, di_relopt_tab, lengthof(di_relopt_tab));
+
+	return (bytea *) rdopts;
+}
+
+/*
+ * Validator for index AM.
+ */
+static bool
+divalidate(Oid opclassoid)
+{
+	/* Index is dummy so we are happy with any opclass */
+	return true;
+}
+
+/*
+ * Begin scan of index AM.
+ */
+static IndexScanDesc
+dibeginscan(Relation r, int nkeys, int norderbys)
+{
+	IndexScanDesc scan;
+
+	/* Let's pretend we are doing something */
+	scan = RelationGetIndexScan(r, nkeys, norderbys);
+	return scan;
+}
+
+/*
+ * Rescan of index AM.
+ */
+static void
+direscan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
+		 ScanKey orderbys, int norderbys)
+{
+	/* nothing to do */
+}
+
+/*
+ * End scan of index AM.
+ */
+static void
+diendscan(IndexScanDesc scan)
+{
+	/* nothing to do */
+}
+
+/*
+ * Index AM handler function: returns IndexAmRoutine with access method
+ * parameters and callbacks.
+ */
+Datum
+dihandler(PG_FUNCTION_ARGS)
+{
+	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
+
+	amroutine->amstrategies = 0;
+	amroutine->amsupport = 1;
+	amroutine->amcanorder = false;
+	amroutine->amcanorderbyop = false;
+	amroutine->amcanbackward = false;
+	amroutine->amcanunique = false;
+	amroutine->amcanmulticol = false;
+	amroutine->amoptionalkey = false;
+	amroutine->amsearcharray = false;
+	amroutine->amsearchnulls = false;
+	amroutine->amstorage = false;
+	amroutine->amclusterable = false;
+	amroutine->ampredlocks = false;
+	amroutine->amcanparallel = false;
+	amroutine->amcaninclude = false;
+	amroutine->amkeytype = InvalidOid;
+
+	amroutine->ambuild = dibuild;
+	amroutine->ambuildempty = dibuildempty;
+	amroutine->aminsert = diinsert;
+	amroutine->ambulkdelete = dibulkdelete;
+	amroutine->amvacuumcleanup = divacuumcleanup;
+	amroutine->amcanreturn = NULL;
+	amroutine->amcostestimate = dicostestimate;
+	amroutine->amoptions = dioptions;
+	amroutine->amproperty = NULL;
+	amroutine->ambuildphasename = NULL;
+	amroutine->amvalidate = divalidate;
+	amroutine->ambeginscan = dibeginscan;
+	amroutine->amrescan = direscan;
+	amroutine->amgettuple = NULL;
+	amroutine->amgetbitmap = NULL;
+	amroutine->amendscan = diendscan;
+	amroutine->ammarkpos = NULL;
+	amroutine->amrestrpos = NULL;
+	amroutine->amestimateparallelscan = NULL;
+	amroutine->aminitparallelscan = NULL;
+	amroutine->amparallelrescan = NULL;
+
+	PG_RETURN_POINTER(amroutine);
+}
+
+void
+_PG_init(void)
+{
+	create_reloptions_table();
+}
diff --git a/src/test/modules/dummy_index_am/dummy_index_am.control b/src/test/modules/dummy_index_am/dummy_index_am.control
new file mode 100644
index 0000000000..77bdea08ae
--- /dev/null
+++ b/src/test/modules/dummy_index_am/dummy_index_am.control
@@ -0,0 +1,5 @@
+# dummy_index_am extension
+comment = 'dummy_index_am - index access method template'
+default_version = '1.0'
+module_pathname = '$libdir/dummy_index_am'
+relocatable = true
diff --git a/src/test/modules/dummy_index_am/expected/reloptions.out b/src/test/modules/dummy_index_am/expected/reloptions.out
new file mode 100644
index 0000000000..04a120a0e0
--- /dev/null
+++ b/src/test/modules/dummy_index_am/expected/reloptions.out
@@ -0,0 +1,77 @@
+-- Tests for relation options
+CREATE EXTENSION dummy_index_am;
+CREATE TABLE dummy_test_tab (i int4);
+-- Test with default values.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+ unnest 
+--------
+(0 rows)
+
+DROP INDEX dummy_test_idx;
+-- Test with full set of options.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i) WITH (
+  option_bool = false,
+  option_int = 5,
+  option_real = 3.1,
+  option_string_val = NULL,
+  option_string_null = 'val');
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+         unnest         
+------------------------
+ option_bool=false
+ option_int=5
+ option_real=3.1
+ option_string_val=null
+ option_string_null=val
+(5 rows)
+
+-- ALTER INDEX .. SET
+ALTER INDEX dummy_test_idx SET (option_int = 10);
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+ALTER INDEX dummy_test_idx SET (option_bool = true);
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+ALTER INDEX dummy_test_idx SET (option_real = 3.2);
+NOTICE:  new option value for string parameter null
+NOTICE:  new option value for string parameter val
+ALTER INDEX dummy_test_idx SET (option_string_val = 'val2');
+NOTICE:  new option value for string parameter val
+NOTICE:  new option value for string parameter val2
+ALTER INDEX dummy_test_idx SET (option_string_null = NULL);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+         unnest          
+-------------------------
+ option_int=10
+ option_bool=true
+ option_real=3.2
+ option_string_val=val2
+ option_string_null=null
+(5 rows)
+
+-- ALTER INDEX .. RESET
+ALTER INDEX dummy_test_idx RESET (option_int);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_bool);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_real);
+NOTICE:  new option value for string parameter val2
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_string_val);
+NOTICE:  new option value for string parameter null
+ALTER INDEX dummy_test_idx RESET (option_string_null);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+ unnest 
+--------
+(0 rows)
+
+DROP INDEX dummy_test_idx;
diff --git a/src/test/modules/dummy_index_am/sql/reloptions.sql b/src/test/modules/dummy_index_am/sql/reloptions.sql
new file mode 100644
index 0000000000..10ca1a6d03
--- /dev/null
+++ b/src/test/modules/dummy_index_am/sql/reloptions.sql
@@ -0,0 +1,38 @@
+-- Tests for relation options
+CREATE EXTENSION dummy_index_am;
+
+CREATE TABLE dummy_test_tab (i int4);
+
+-- Test with default values.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+DROP INDEX dummy_test_idx;
+
+-- Test with full set of options.
+CREATE INDEX dummy_test_idx ON dummy_test_tab
+  USING dummy_index_am (i) WITH (
+  option_bool = false,
+  option_int = 5,
+  option_real = 3.1,
+  option_string_val = NULL,
+  option_string_null = 'val');
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+
+-- ALTER INDEX .. SET
+ALTER INDEX dummy_test_idx SET (option_int = 10);
+ALTER INDEX dummy_test_idx SET (option_bool = true);
+ALTER INDEX dummy_test_idx SET (option_real = 3.2);
+ALTER INDEX dummy_test_idx SET (option_string_val = 'val2');
+ALTER INDEX dummy_test_idx SET (option_string_null = NULL);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+
+-- ALTER INDEX .. RESET
+ALTER INDEX dummy_test_idx RESET (option_int);
+ALTER INDEX dummy_test_idx RESET (option_bool);
+ALTER INDEX dummy_test_idx RESET (option_real);
+ALTER INDEX dummy_test_idx RESET (option_string_val);
+ALTER INDEX dummy_test_idx RESET (option_string_null);
+SELECT unnest(reloptions) FROM pg_class WHERE relname = 'dummy_test_idx';
+
+DROP INDEX dummy_test_idx;
-- 
2.23.0