v1-0001-Stop-heap-allocating-IndexAmRoutine-for-every-ind.patch

From 206d5c0da8acfa749744ecc8f12cd83bf940dd82 Mon Sep 17 00:00:00 2001
From: Matthias van de Meent <boekewurm+postgres@gmail.com>
Date: Sat, 10 May 2025 12:38:46 +0200
Subject: [PATCH v1 1/2] Stop heap-allocating IndexAmRoutine for every index

By making every IndexAmRoutine a static const*, we save a lot of memory.
---
 contrib/bloom/blutils.c                       | 111 ++++++++---------
 src/backend/access/brin/brin.c                | 113 +++++++++---------
 src/backend/access/gin/ginutil.c              | 109 ++++++++---------
 src/backend/access/gist/gist.c                | 113 +++++++++---------
 src/backend/access/hash/hash.c                | 113 +++++++++---------
 src/backend/access/index/amapi.c              |  12 +-
 src/backend/access/nbtree/nbtree.c            | 113 +++++++++---------
 src/backend/access/spgist/spgutils.c          | 113 +++++++++---------
 src/backend/catalog/index.c                   |   4 +-
 src/backend/commands/indexcmds.c              |   5 +-
 src/backend/commands/opclasscmds.c            |   8 +-
 src/backend/executor/execAmi.c                |   3 +-
 src/backend/optimizer/util/plancat.c          |   2 +-
 src/backend/utils/adt/amutils.c               |   4 +-
 src/backend/utils/adt/ruleutils.c             |   2 +-
 src/backend/utils/cache/lsyscache.c           |   9 +-
 src/backend/utils/cache/relcache.c            |  17 +--
 src/include/access/amapi.h                    |   4 +-
 src/include/utils/rel.h                       |   2 +-
 .../modules/dummy_index_am/dummy_index_am.c   | 101 ++++++++--------
 20 files changed, 472 insertions(+), 486 deletions(-)

diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 2c0e71eedc6..7b45993e096 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -102,61 +102,62 @@ makeDefaultBloomOptions(void)
 Datum
 blhandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = BLOOM_NSTRATEGIES;
-	amroutine->amsupport = BLOOM_NPROC;
-	amroutine->amoptsprocnum = BLOOM_OPTIONS_PROC;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = false;
-	amroutine->amconsistentordering = false;
-	amroutine->amcanbackward = false;
-	amroutine->amcanunique = false;
-	amroutine->amcanmulticol = true;
-	amroutine->amoptionalkey = true;
-	amroutine->amsearcharray = false;
-	amroutine->amsearchnulls = false;
-	amroutine->amstorage = false;
-	amroutine->amclusterable = false;
-	amroutine->ampredlocks = false;
-	amroutine->amcanparallel = false;
-	amroutine->amcanbuildparallel = false;
-	amroutine->amcaninclude = false;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP;
-	amroutine->amkeytype = InvalidOid;
-
-	amroutine->ambuild = blbuild;
-	amroutine->ambuildempty = blbuildempty;
-	amroutine->aminsert = blinsert;
-	amroutine->aminsertcleanup = NULL;
-	amroutine->ambulkdelete = blbulkdelete;
-	amroutine->amvacuumcleanup = blvacuumcleanup;
-	amroutine->amcanreturn = NULL;
-	amroutine->amcostestimate = blcostestimate;
-	amroutine->amgettreeheight = NULL;
-	amroutine->amoptions = bloptions;
-	amroutine->amproperty = NULL;
-	amroutine->ambuildphasename = NULL;
-	amroutine->amvalidate = blvalidate;
-	amroutine->amadjustmembers = NULL;
-	amroutine->ambeginscan = blbeginscan;
-	amroutine->amrescan = blrescan;
-	amroutine->amgettuple = NULL;
-	amroutine->amgetbitmap = blgetbitmap;
-	amroutine->amendscan = blendscan;
-	amroutine->ammarkpos = NULL;
-	amroutine->amrestrpos = NULL;
-	amroutine->amestimateparallelscan = NULL;
-	amroutine->aminitparallelscan = NULL;
-	amroutine->amparallelrescan = NULL;
-	amroutine->amtranslatestrategy = NULL;
-	amroutine->amtranslatecmptype = NULL;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = BLOOM_NSTRATEGIES,
+		.amsupport = BLOOM_NPROC,
+		.amoptsprocnum = BLOOM_OPTIONS_PROC,
+		.amcanorder = false,
+		.amcanorderbyop = false,
+		.amcanhash = false,
+		.amconsistentequality = false,
+		.amconsistentordering = false,
+		.amcanbackward = false,
+		.amcanunique = false,
+		.amcanmulticol = true,
+		.amoptionalkey = true,
+		.amsearcharray = false,
+		.amsearchnulls = false,
+		.amstorage = false,
+		.amclusterable = false,
+		.ampredlocks = false,
+		.amcanparallel = false,
+		.amcanbuildparallel = false,
+		.amcaninclude = false,
+		.amusemaintenanceworkmem = false,
+		.amparallelvacuumoptions =
+		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP,
+		.amkeytype = InvalidOid,
+
+		.ambuild = blbuild,
+		.ambuildempty = blbuildempty,
+		.aminsert = blinsert,
+		.aminsertcleanup = NULL,
+		.ambulkdelete = blbulkdelete,
+		.amvacuumcleanup = blvacuumcleanup,
+		.amcanreturn = NULL,
+		.amcostestimate = blcostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = bloptions,
+		.amproperty = NULL,
+		.ambuildphasename = NULL,
+		.amvalidate = blvalidate,
+		.amadjustmembers = NULL,
+		.ambeginscan = blbeginscan,
+		.amrescan = blrescan,
+		.amgettuple = NULL,
+		.amgetbitmap = blgetbitmap,
+		.amendscan = blendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+		.amtranslatestrategy = NULL,
+		.amtranslatecmptype = NULL,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 01e1db7f856..22a24db49a7 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -249,62 +249,63 @@ static void _brin_parallel_scan_and_build(BrinBuildState *state,
 Datum
 brinhandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = 0;
-	amroutine->amsupport = BRIN_LAST_OPTIONAL_PROCNUM;
-	amroutine->amoptsprocnum = BRIN_PROCNUM_OPTIONS;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = false;
-	amroutine->amconsistentordering = false;
-	amroutine->amcanbackward = false;
-	amroutine->amcanunique = false;
-	amroutine->amcanmulticol = true;
-	amroutine->amoptionalkey = true;
-	amroutine->amsearcharray = false;
-	amroutine->amsearchnulls = true;
-	amroutine->amstorage = true;
-	amroutine->amclusterable = false;
-	amroutine->ampredlocks = false;
-	amroutine->amcanparallel = false;
-	amroutine->amcanbuildparallel = true;
-	amroutine->amcaninclude = false;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amsummarizing = true;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_CLEANUP;
-	amroutine->amkeytype = InvalidOid;
-
-	amroutine->ambuild = brinbuild;
-	amroutine->ambuildempty = brinbuildempty;
-	amroutine->aminsert = brininsert;
-	amroutine->aminsertcleanup = brininsertcleanup;
-	amroutine->ambulkdelete = brinbulkdelete;
-	amroutine->amvacuumcleanup = brinvacuumcleanup;
-	amroutine->amcanreturn = NULL;
-	amroutine->amcostestimate = brincostestimate;
-	amroutine->amgettreeheight = NULL;
-	amroutine->amoptions = brinoptions;
-	amroutine->amproperty = NULL;
-	amroutine->ambuildphasename = NULL;
-	amroutine->amvalidate = brinvalidate;
-	amroutine->amadjustmembers = NULL;
-	amroutine->ambeginscan = brinbeginscan;
-	amroutine->amrescan = brinrescan;
-	amroutine->amgettuple = NULL;
-	amroutine->amgetbitmap = bringetbitmap;
-	amroutine->amendscan = brinendscan;
-	amroutine->ammarkpos = NULL;
-	amroutine->amrestrpos = NULL;
-	amroutine->amestimateparallelscan = NULL;
-	amroutine->aminitparallelscan = NULL;
-	amroutine->amparallelrescan = NULL;
-	amroutine->amtranslatestrategy = NULL;
-	amroutine->amtranslatecmptype = NULL;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = 0,
+		.amsupport = BRIN_LAST_OPTIONAL_PROCNUM,
+		.amoptsprocnum = BRIN_PROCNUM_OPTIONS,
+		.amcanorder = false,
+		.amcanorderbyop = false,
+		.amcanhash = false,
+		.amconsistentequality = false,
+		.amconsistentordering = false,
+		.amcanbackward = false,
+		.amcanunique = false,
+		.amcanmulticol = true,
+		.amoptionalkey = true,
+		.amsearcharray = false,
+		.amsearchnulls = true,
+		.amstorage = true,
+		.amclusterable = false,
+		.ampredlocks = false,
+		.amcanparallel = false,
+		.amcanbuildparallel = true,
+		.amcaninclude = false,
+		.amusemaintenanceworkmem = false,
+		.amsummarizing = true,
+		.amparallelvacuumoptions =
+			VACUUM_OPTION_PARALLEL_CLEANUP,
+		.amkeytype = InvalidOid,
+
+		.ambuild = brinbuild,
+		.ambuildempty = brinbuildempty,
+		.aminsert = brininsert,
+		.aminsertcleanup = brininsertcleanup,
+		.ambulkdelete = brinbulkdelete,
+		.amvacuumcleanup = brinvacuumcleanup,
+		.amcanreturn = NULL,
+		.amcostestimate = brincostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = brinoptions,
+		.amproperty = NULL,
+		.ambuildphasename = NULL,
+		.amvalidate = brinvalidate,
+		.amadjustmembers = NULL,
+		.ambeginscan = brinbeginscan,
+		.amrescan = brinrescan,
+		.amgettuple = NULL,
+		.amgetbitmap = bringetbitmap,
+		.amendscan = brinendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+		.amtranslatestrategy = NULL,
+		.amtranslatecmptype = NULL,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/access/gin/ginutil.c b/src/backend/access/gin/ginutil.c
index 78f7b7a2495..5b086faf465 100644
--- a/src/backend/access/gin/ginutil.c
+++ b/src/backend/access/gin/ginutil.c
@@ -37,60 +37,61 @@
 Datum
 ginhandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = 0;
-	amroutine->amsupport = GINNProcs;
-	amroutine->amoptsprocnum = GIN_OPTIONS_PROC;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = false;
-	amroutine->amconsistentordering = false;
-	amroutine->amcanbackward = false;
-	amroutine->amcanunique = false;
-	amroutine->amcanmulticol = true;
-	amroutine->amoptionalkey = true;
-	amroutine->amsearcharray = false;
-	amroutine->amsearchnulls = false;
-	amroutine->amstorage = true;
-	amroutine->amclusterable = false;
-	amroutine->ampredlocks = true;
-	amroutine->amcanparallel = false;
-	amroutine->amcanbuildparallel = true;
-	amroutine->amcaninclude = false;
-	amroutine->amusemaintenanceworkmem = true;
-	amroutine->amsummarizing = false;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP;
-	amroutine->amkeytype = InvalidOid;
-
-	amroutine->ambuild = ginbuild;
-	amroutine->ambuildempty = ginbuildempty;
-	amroutine->aminsert = gininsert;
-	amroutine->aminsertcleanup = NULL;
-	amroutine->ambulkdelete = ginbulkdelete;
-	amroutine->amvacuumcleanup = ginvacuumcleanup;
-	amroutine->amcanreturn = NULL;
-	amroutine->amcostestimate = gincostestimate;
-	amroutine->amgettreeheight = NULL;
-	amroutine->amoptions = ginoptions;
-	amroutine->amproperty = NULL;
-	amroutine->ambuildphasename = ginbuildphasename;
-	amroutine->amvalidate = ginvalidate;
-	amroutine->amadjustmembers = ginadjustmembers;
-	amroutine->ambeginscan = ginbeginscan;
-	amroutine->amrescan = ginrescan;
-	amroutine->amgettuple = NULL;
-	amroutine->amgetbitmap = gingetbitmap;
-	amroutine->amendscan = ginendscan;
-	amroutine->ammarkpos = NULL;
-	amroutine->amrestrpos = NULL;
-	amroutine->amestimateparallelscan = NULL;
-	amroutine->aminitparallelscan = NULL;
-	amroutine->amparallelrescan = NULL;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = 0,
+		.amsupport = GINNProcs,
+		.amoptsprocnum = GIN_OPTIONS_PROC,
+		.amcanorder = false,
+		.amcanorderbyop = false,
+		.amcanhash = false,
+		.amconsistentequality = false,
+		.amconsistentordering = false,
+		.amcanbackward = false,
+		.amcanunique = false,
+		.amcanmulticol = true,
+		.amoptionalkey = true,
+		.amsearcharray = false,
+		.amsearchnulls = false,
+		.amstorage = true,
+		.amclusterable = false,
+		.ampredlocks = true,
+		.amcanparallel = false,
+		.amcanbuildparallel = true,
+		.amcaninclude = false,
+		.amusemaintenanceworkmem = true,
+		.amsummarizing = false,
+		.amparallelvacuumoptions =
+			VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP,
+		.amkeytype = InvalidOid,
+
+		.ambuild = ginbuild,
+		.ambuildempty = ginbuildempty,
+		.aminsert = gininsert,
+		.aminsertcleanup = NULL,
+		.ambulkdelete = ginbulkdelete,
+		.amvacuumcleanup = ginvacuumcleanup,
+		.amcanreturn = NULL,
+		.amcostestimate = gincostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = ginoptions,
+		.amproperty = NULL,
+		.ambuildphasename = ginbuildphasename,
+		.amvalidate = ginvalidate,
+		.amadjustmembers = ginadjustmembers,
+		.ambeginscan = ginbeginscan,
+		.amrescan = ginrescan,
+		.amgettuple = NULL,
+		.amgetbitmap = gingetbitmap,
+		.amendscan = ginendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c
index 7b24380c978..3641b41f7cf 100644
--- a/src/backend/access/gist/gist.c
+++ b/src/backend/access/gist/gist.c
@@ -58,62 +58,63 @@ static void gistprunepage(Relation rel, Page page, Buffer buffer,
 Datum
 gisthandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = 0;
-	amroutine->amsupport = GISTNProcs;
-	amroutine->amoptsprocnum = GIST_OPTIONS_PROC;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = true;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = false;
-	amroutine->amconsistentordering = false;
-	amroutine->amcanbackward = false;
-	amroutine->amcanunique = false;
-	amroutine->amcanmulticol = true;
-	amroutine->amoptionalkey = true;
-	amroutine->amsearcharray = false;
-	amroutine->amsearchnulls = true;
-	amroutine->amstorage = true;
-	amroutine->amclusterable = true;
-	amroutine->ampredlocks = true;
-	amroutine->amcanparallel = false;
-	amroutine->amcanbuildparallel = false;
-	amroutine->amcaninclude = true;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amsummarizing = false;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
-	amroutine->amkeytype = InvalidOid;
-
-	amroutine->ambuild = gistbuild;
-	amroutine->ambuildempty = gistbuildempty;
-	amroutine->aminsert = gistinsert;
-	amroutine->aminsertcleanup = NULL;
-	amroutine->ambulkdelete = gistbulkdelete;
-	amroutine->amvacuumcleanup = gistvacuumcleanup;
-	amroutine->amcanreturn = gistcanreturn;
-	amroutine->amcostestimate = gistcostestimate;
-	amroutine->amgettreeheight = NULL;
-	amroutine->amoptions = gistoptions;
-	amroutine->amproperty = gistproperty;
-	amroutine->ambuildphasename = NULL;
-	amroutine->amvalidate = gistvalidate;
-	amroutine->amadjustmembers = gistadjustmembers;
-	amroutine->ambeginscan = gistbeginscan;
-	amroutine->amrescan = gistrescan;
-	amroutine->amgettuple = gistgettuple;
-	amroutine->amgetbitmap = gistgetbitmap;
-	amroutine->amendscan = gistendscan;
-	amroutine->ammarkpos = NULL;
-	amroutine->amrestrpos = NULL;
-	amroutine->amestimateparallelscan = NULL;
-	amroutine->aminitparallelscan = NULL;
-	amroutine->amparallelrescan = NULL;
-	amroutine->amtranslatestrategy = NULL;
-	amroutine->amtranslatecmptype = gisttranslatecmptype;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = 0,
+		.amsupport = GISTNProcs,
+		.amoptsprocnum = GIST_OPTIONS_PROC,
+		.amcanorder = false,
+		.amcanorderbyop = true,
+		.amcanhash = false,
+		.amconsistentequality = false,
+		.amconsistentordering = false,
+		.amcanbackward = false,
+		.amcanunique = false,
+		.amcanmulticol = true,
+		.amoptionalkey = true,
+		.amsearcharray = false,
+		.amsearchnulls = true,
+		.amstorage = true,
+		.amclusterable = true,
+		.ampredlocks = true,
+		.amcanparallel = false,
+		.amcanbuildparallel = false,
+		.amcaninclude = true,
+		.amusemaintenanceworkmem = false,
+		.amsummarizing = false,
+		.amparallelvacuumoptions =
+			VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP,
+		.amkeytype = InvalidOid,
+
+		.ambuild = gistbuild,
+		.ambuildempty = gistbuildempty,
+		.aminsert = gistinsert,
+		.aminsertcleanup = NULL,
+		.ambulkdelete = gistbulkdelete,
+		.amvacuumcleanup = gistvacuumcleanup,
+		.amcanreturn = gistcanreturn,
+		.amcostestimate = gistcostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = gistoptions,
+		.amproperty = gistproperty,
+		.ambuildphasename = NULL,
+		.amvalidate = gistvalidate,
+		.amadjustmembers = gistadjustmembers,
+		.ambeginscan = gistbeginscan,
+		.amrescan = gistrescan,
+		.amgettuple = gistgettuple,
+		.amgetbitmap = gistgetbitmap,
+		.amendscan = gistendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+		.amtranslatestrategy = NULL,
+		.amtranslatecmptype = gisttranslatecmptype,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index 53061c819fb..353fc03b989 100644
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -57,62 +57,63 @@ static void hashbuildCallback(Relation index,
 Datum
 hashhandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = HTMaxStrategyNumber;
-	amroutine->amsupport = HASHNProcs;
-	amroutine->amoptsprocnum = HASHOPTIONS_PROC;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
-	amroutine->amcanhash = true;
-	amroutine->amconsistentequality = true;
-	amroutine->amconsistentordering = false;
-	amroutine->amcanbackward = true;
-	amroutine->amcanunique = false;
-	amroutine->amcanmulticol = false;
-	amroutine->amoptionalkey = false;
-	amroutine->amsearcharray = false;
-	amroutine->amsearchnulls = false;
-	amroutine->amstorage = false;
-	amroutine->amclusterable = false;
-	amroutine->ampredlocks = true;
-	amroutine->amcanparallel = false;
-	amroutine->amcanbuildparallel = false;
-	amroutine->amcaninclude = false;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amsummarizing = false;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_BULKDEL;
-	amroutine->amkeytype = INT4OID;
-
-	amroutine->ambuild = hashbuild;
-	amroutine->ambuildempty = hashbuildempty;
-	amroutine->aminsert = hashinsert;
-	amroutine->aminsertcleanup = NULL;
-	amroutine->ambulkdelete = hashbulkdelete;
-	amroutine->amvacuumcleanup = hashvacuumcleanup;
-	amroutine->amcanreturn = NULL;
-	amroutine->amcostestimate = hashcostestimate;
-	amroutine->amgettreeheight = NULL;
-	amroutine->amoptions = hashoptions;
-	amroutine->amproperty = NULL;
-	amroutine->ambuildphasename = NULL;
-	amroutine->amvalidate = hashvalidate;
-	amroutine->amadjustmembers = hashadjustmembers;
-	amroutine->ambeginscan = hashbeginscan;
-	amroutine->amrescan = hashrescan;
-	amroutine->amgettuple = hashgettuple;
-	amroutine->amgetbitmap = hashgetbitmap;
-	amroutine->amendscan = hashendscan;
-	amroutine->ammarkpos = NULL;
-	amroutine->amrestrpos = NULL;
-	amroutine->amestimateparallelscan = NULL;
-	amroutine->aminitparallelscan = NULL;
-	amroutine->amparallelrescan = NULL;
-	amroutine->amtranslatestrategy = hashtranslatestrategy;
-	amroutine->amtranslatecmptype = hashtranslatecmptype;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = HTMaxStrategyNumber,
+		.amsupport = HASHNProcs,
+		.amoptsprocnum = HASHOPTIONS_PROC,
+		.amcanorder = false,
+		.amcanorderbyop = false,
+		.amcanhash = true,
+		.amconsistentequality = true,
+		.amconsistentordering = false,
+		.amcanbackward = true,
+		.amcanunique = false,
+		.amcanmulticol = false,
+		.amoptionalkey = false,
+		.amsearcharray = false,
+		.amsearchnulls = false,
+		.amstorage = false,
+		.amclusterable = false,
+		.ampredlocks = true,
+		.amcanparallel = false,
+		.amcanbuildparallel = false,
+		.amcaninclude = false,
+		.amusemaintenanceworkmem = false,
+		.amsummarizing = false,
+		.amparallelvacuumoptions =
+			VACUUM_OPTION_PARALLEL_BULKDEL,
+		.amkeytype = INT4OID,
+	
+		.ambuild = hashbuild,
+		.ambuildempty = hashbuildempty,
+		.aminsert = hashinsert,
+		.aminsertcleanup = NULL,
+		.ambulkdelete = hashbulkdelete,
+		.amvacuumcleanup = hashvacuumcleanup,
+		.amcanreturn = NULL,
+		.amcostestimate = hashcostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = hashoptions,
+		.amproperty = NULL,
+		.ambuildphasename = NULL,
+		.amvalidate = hashvalidate,
+		.amadjustmembers = hashadjustmembers,
+		.ambeginscan = hashbeginscan,
+		.amrescan = hashrescan,
+		.amgettuple = hashgettuple,
+		.amgetbitmap = hashgetbitmap,
+		.amendscan = hashendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+		.amtranslatestrategy = hashtranslatestrategy,
+		.amtranslatecmptype = hashtranslatecmptype,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/access/index/amapi.c b/src/backend/access/index/amapi.c
index f0f4f974bce..40e8c88924a 100644
--- a/src/backend/access/index/amapi.c
+++ b/src/backend/access/index/amapi.c
@@ -29,7 +29,7 @@
  * any catalog access.  It's therefore safe to use this while bootstrapping
  * indexes for the system catalogs.  relcache.c relies on that.
  */
-IndexAmRoutine *
+const IndexAmRoutine *
 GetIndexAmRoutine(Oid amhandler)
 {
 	Datum		datum;
@@ -52,7 +52,7 @@ GetIndexAmRoutine(Oid amhandler)
  * If the given OID isn't a valid index access method, returns NULL if
  * noerror is true, else throws error.
  */
-IndexAmRoutine *
+const IndexAmRoutine *
 GetIndexAmRoutineByAmId(Oid amoid, bool noerror)
 {
 	HeapTuple	tuple;
@@ -118,7 +118,7 @@ CompareType
 IndexAmTranslateStrategy(StrategyNumber strategy, Oid amoid, Oid opfamily, bool missing_ok)
 {
 	CompareType result;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 
 	/* shortcut for common case */
 	if (amoid == BTREE_AM_OID &&
@@ -148,7 +148,7 @@ StrategyNumber
 IndexAmTranslateCompareType(CompareType cmptype, Oid amoid, Oid opfamily, bool missing_ok)
 {
 	StrategyNumber result;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 
 	/* shortcut for common case */
 	if (amoid == BTREE_AM_OID &&
@@ -178,7 +178,7 @@ amvalidate(PG_FUNCTION_ARGS)
 	HeapTuple	classtup;
 	Form_pg_opclass classform;
 	Oid			amoid;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 
 	classtup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclassoid));
 	if (!HeapTupleIsValid(classtup))
@@ -197,7 +197,5 @@ amvalidate(PG_FUNCTION_ARGS)
 
 	result = amroutine->amvalidate(opclassoid);
 
-	pfree(amroutine);
-
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 765659887af..f89067c90bd 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -114,62 +114,63 @@ static BTVacuumPosting btreevacuumposting(BTVacState *vstate,
 Datum
 bthandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = BTMaxStrategyNumber;
-	amroutine->amsupport = BTNProcs;
-	amroutine->amoptsprocnum = BTOPTIONS_PROC;
-	amroutine->amcanorder = true;
-	amroutine->amcanorderbyop = false;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = true;
-	amroutine->amconsistentordering = true;
-	amroutine->amcanbackward = true;
-	amroutine->amcanunique = true;
-	amroutine->amcanmulticol = true;
-	amroutine->amoptionalkey = true;
-	amroutine->amsearcharray = true;
-	amroutine->amsearchnulls = true;
-	amroutine->amstorage = false;
-	amroutine->amclusterable = true;
-	amroutine->ampredlocks = true;
-	amroutine->amcanparallel = true;
-	amroutine->amcanbuildparallel = true;
-	amroutine->amcaninclude = true;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amsummarizing = false;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
-	amroutine->amkeytype = InvalidOid;
-
-	amroutine->ambuild = btbuild;
-	amroutine->ambuildempty = btbuildempty;
-	amroutine->aminsert = btinsert;
-	amroutine->aminsertcleanup = NULL;
-	amroutine->ambulkdelete = btbulkdelete;
-	amroutine->amvacuumcleanup = btvacuumcleanup;
-	amroutine->amcanreturn = btcanreturn;
-	amroutine->amcostestimate = btcostestimate;
-	amroutine->amgettreeheight = btgettreeheight;
-	amroutine->amoptions = btoptions;
-	amroutine->amproperty = btproperty;
-	amroutine->ambuildphasename = btbuildphasename;
-	amroutine->amvalidate = btvalidate;
-	amroutine->amadjustmembers = btadjustmembers;
-	amroutine->ambeginscan = btbeginscan;
-	amroutine->amrescan = btrescan;
-	amroutine->amgettuple = btgettuple;
-	amroutine->amgetbitmap = btgetbitmap;
-	amroutine->amendscan = btendscan;
-	amroutine->ammarkpos = btmarkpos;
-	amroutine->amrestrpos = btrestrpos;
-	amroutine->amestimateparallelscan = btestimateparallelscan;
-	amroutine->aminitparallelscan = btinitparallelscan;
-	amroutine->amparallelrescan = btparallelrescan;
-	amroutine->amtranslatestrategy = bttranslatestrategy;
-	amroutine->amtranslatecmptype = bttranslatecmptype;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = BTMaxStrategyNumber,
+		.amsupport = BTNProcs,
+		.amoptsprocnum = BTOPTIONS_PROC,
+		.amcanorder = true,
+		.amcanorderbyop = false,
+		.amcanhash = false,
+		.amconsistentequality = true,
+		.amconsistentordering = true,
+		.amcanbackward = true,
+		.amcanunique = true,
+		.amcanmulticol = true,
+		.amoptionalkey = true,
+		.amsearcharray = true,
+		.amsearchnulls = true,
+		.amstorage = false,
+		.amclusterable = true,
+		.ampredlocks = true,
+		.amcanparallel = true,
+		.amcanbuildparallel = true,
+		.amcaninclude = true,
+		.amusemaintenanceworkmem = false,
+		.amsummarizing = false,
+		.amparallelvacuumoptions =
+		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP,
+		.amkeytype = InvalidOid,
+
+		.ambuild = btbuild,
+		.ambuildempty = btbuildempty,
+		.aminsert = btinsert,
+		.aminsertcleanup = NULL,
+		.ambulkdelete = btbulkdelete,
+		.amvacuumcleanup = btvacuumcleanup,
+		.amcanreturn = btcanreturn,
+		.amcostestimate = btcostestimate,
+		.amgettreeheight = btgettreeheight,
+		.amoptions = btoptions,
+		.amproperty = btproperty,
+		.ambuildphasename = btbuildphasename,
+		.amvalidate = btvalidate,
+		.amadjustmembers = btadjustmembers,
+		.ambeginscan = btbeginscan,
+		.amrescan = btrescan,
+		.amgettuple = btgettuple,
+		.amgetbitmap = btgetbitmap,
+		.amendscan = btendscan,
+		.ammarkpos = btmarkpos,
+		.amrestrpos = btrestrpos,
+		.amestimateparallelscan = btestimateparallelscan,
+		.aminitparallelscan = btinitparallelscan,
+		.amparallelrescan = btparallelrescan,
+		.amtranslatestrategy = bttranslatestrategy,
+		.amtranslatecmptype = bttranslatecmptype,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/access/spgist/spgutils.c b/src/backend/access/spgist/spgutils.c
index 95fea74e296..935d7afbbde 100644
--- a/src/backend/access/spgist/spgutils.c
+++ b/src/backend/access/spgist/spgutils.c
@@ -43,62 +43,63 @@
 Datum
 spghandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = 0;
-	amroutine->amsupport = SPGISTNProc;
-	amroutine->amoptsprocnum = SPGIST_OPTIONS_PROC;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = true;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = false;
-	amroutine->amconsistentordering = false;
-	amroutine->amcanbackward = false;
-	amroutine->amcanunique = false;
-	amroutine->amcanmulticol = false;
-	amroutine->amoptionalkey = true;
-	amroutine->amsearcharray = false;
-	amroutine->amsearchnulls = true;
-	amroutine->amstorage = true;
-	amroutine->amclusterable = false;
-	amroutine->ampredlocks = false;
-	amroutine->amcanparallel = false;
-	amroutine->amcanbuildparallel = false;
-	amroutine->amcaninclude = true;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amsummarizing = false;
-	amroutine->amparallelvacuumoptions =
-		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
-	amroutine->amkeytype = InvalidOid;
-
-	amroutine->ambuild = spgbuild;
-	amroutine->ambuildempty = spgbuildempty;
-	amroutine->aminsert = spginsert;
-	amroutine->aminsertcleanup = NULL;
-	amroutine->ambulkdelete = spgbulkdelete;
-	amroutine->amvacuumcleanup = spgvacuumcleanup;
-	amroutine->amcanreturn = spgcanreturn;
-	amroutine->amcostestimate = spgcostestimate;
-	amroutine->amgettreeheight = NULL;
-	amroutine->amoptions = spgoptions;
-	amroutine->amproperty = spgproperty;
-	amroutine->ambuildphasename = NULL;
-	amroutine->amvalidate = spgvalidate;
-	amroutine->amadjustmembers = spgadjustmembers;
-	amroutine->ambeginscan = spgbeginscan;
-	amroutine->amrescan = spgrescan;
-	amroutine->amgettuple = spggettuple;
-	amroutine->amgetbitmap = spggetbitmap;
-	amroutine->amendscan = spgendscan;
-	amroutine->ammarkpos = NULL;
-	amroutine->amrestrpos = NULL;
-	amroutine->amestimateparallelscan = NULL;
-	amroutine->aminitparallelscan = NULL;
-	amroutine->amparallelrescan = NULL;
-	amroutine->amtranslatestrategy = NULL;
-	amroutine->amtranslatecmptype = NULL;
-
-	PG_RETURN_POINTER(amroutine);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = 0,
+		.amsupport = SPGISTNProc,
+		.amoptsprocnum = SPGIST_OPTIONS_PROC,
+		.amcanorder = false,
+		.amcanorderbyop = true,
+		.amcanhash = false,
+		.amconsistentequality = false,
+		.amconsistentordering = false,
+		.amcanbackward = false,
+		.amcanunique = false,
+		.amcanmulticol = false,
+		.amoptionalkey = true,
+		.amsearcharray = false,
+		.amsearchnulls = true,
+		.amstorage = true,
+		.amclusterable = false,
+		.ampredlocks = false,
+		.amcanparallel = false,
+		.amcanbuildparallel = false,
+		.amcaninclude = true,
+		.amusemaintenanceworkmem = false,
+		.amsummarizing = false,
+		.amparallelvacuumoptions =
+		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP,
+		.amkeytype = InvalidOid,
+
+		.ambuild = spgbuild,
+		.ambuildempty = spgbuildempty,
+		.aminsert = spginsert,
+		.aminsertcleanup = NULL,
+		.ambulkdelete = spgbulkdelete,
+		.amvacuumcleanup = spgvacuumcleanup,
+		.amcanreturn = spgcanreturn,
+		.amcostestimate = spgcostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = spgoptions,
+		.amproperty = spgproperty,
+		.ambuildphasename = NULL,
+		.amvalidate = spgvalidate,
+		.amadjustmembers = spgadjustmembers,
+		.ambeginscan = spgbeginscan,
+		.amrescan = spgrescan,
+		.amgettuple = spggettuple,
+		.amgetbitmap = spggetbitmap,
+		.amendscan = spgendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+		.amtranslatestrategy = NULL,
+		.amtranslatecmptype = NULL,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 /*
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 739a92bdcc1..8253d9a8ddb 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -289,7 +289,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 	int			numkeyatts = indexInfo->ii_NumIndexKeyAttrs;
 	ListCell   *colnames_item = list_head(indexColNames);
 	ListCell   *indexpr_item = list_head(indexInfo->ii_Expressions);
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 	TupleDesc	heapTupDesc;
 	TupleDesc	indexTupDesc;
 	int			natts;			/* #atts in heap rel --- for error checks */
@@ -481,8 +481,6 @@ ConstructTupleDescriptor(Relation heapRelation,
 		populate_compact_attribute(indexTupDesc, i);
 	}
 
-	pfree(amroutine);
-
 	return indexTupDesc;
 }
 
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 33c2106c17c..e4caeac0147 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -191,7 +191,7 @@ CheckIndexCompatible(Oid oldId,
 	HeapTuple	tuple;
 	Form_pg_index indexForm;
 	Form_pg_am	accessMethodForm;
-	IndexAmRoutine *amRoutine;
+	const IndexAmRoutine *amRoutine;
 	bool		amcanorder;
 	bool		amsummarizing;
 	int16	   *coloptions;
@@ -567,7 +567,7 @@ DefineIndex(Oid tableId,
 	Relation	rel;
 	HeapTuple	tuple;
 	Form_pg_am	accessMethodForm;
-	IndexAmRoutine *amRoutine;
+	const IndexAmRoutine *amRoutine;
 	bool		amcanorder;
 	bool		amissummarizing;
 	amoptions_function amoptions;
@@ -896,7 +896,6 @@ DefineIndex(Oid tableId,
 	amoptions = amRoutine->amoptions;
 	amissummarizing = amRoutine->amsummarizing;
 
-	pfree(amRoutine);
 	ReleaseSysCache(tuple);
 
 	/*
diff --git a/src/backend/commands/opclasscmds.c b/src/backend/commands/opclasscmds.c
index a6dd8eab518..7c85eb5fcc1 100644
--- a/src/backend/commands/opclasscmds.c
+++ b/src/backend/commands/opclasscmds.c
@@ -349,7 +349,7 @@ DefineOpClass(CreateOpClassStmt *stmt)
 	Relation	rel;
 	HeapTuple	tup;
 	Form_pg_am	amform;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 	Datum		values[Natts_pg_opclass];
 	bool		nulls[Natts_pg_opclass];
 	AclResult	aclresult;
@@ -823,7 +823,7 @@ AlterOpFamily(AlterOpFamilyStmt *stmt)
 				maxProcNumber;	/* amsupport value */
 	HeapTuple	tup;
 	Form_pg_am	amform;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 
 	/* Get necessary info about access method */
 	tup = SearchSysCache1(AMNAME, CStringGetDatum(stmt->amname));
@@ -882,7 +882,7 @@ AlterOpFamilyAdd(AlterOpFamilyStmt *stmt, Oid amoid, Oid opfamilyoid,
 				 int maxOpNumber, int maxProcNumber, int optsProcNumber,
 				 List *items)
 {
-	IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
+	const IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
 	List	   *operators;		/* OpFamilyMember list for operators */
 	List	   *procedures;		/* OpFamilyMember list for support procs */
 	ListCell   *l;
@@ -1165,7 +1165,7 @@ assignOperTypes(OpFamilyMember *member, Oid amoid, Oid typeoid)
 		 * the family has been created but not yet populated with the required
 		 * operators.)
 		 */
-		IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
+		const IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
 
 		if (!amroutine->amcanorderbyop)
 			ereport(ERROR,
diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index 1d0e8ad57b4..4893ea3ce91 100644
--- a/src/backend/executor/execAmi.c
+++ b/src/backend/executor/execAmi.c
@@ -605,7 +605,7 @@ IndexSupportsBackwardScan(Oid indexid)
 	bool		result;
 	HeapTuple	ht_idxrel;
 	Form_pg_class idxrelrec;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 
 	/* Fetch the pg_class tuple of the index relation */
 	ht_idxrel = SearchSysCache1(RELOID, ObjectIdGetDatum(indexid));
@@ -618,7 +618,6 @@ IndexSupportsBackwardScan(Oid indexid)
 
 	result = amroutine->amcanbackward;
 
-	pfree(amroutine);
 	ReleaseSysCache(ht_idxrel);
 
 	return result;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 59233b64730..8180a5e418c 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -243,7 +243,7 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 			Oid			indexoid = lfirst_oid(l);
 			Relation	indexRelation;
 			Form_pg_index index;
-			IndexAmRoutine *amroutine = NULL;
+			const IndexAmRoutine *amroutine = NULL;
 			IndexOptInfo *info;
 			int			ncolumns,
 						nkeycolumns;
diff --git a/src/backend/utils/adt/amutils.c b/src/backend/utils/adt/amutils.c
index 0af26d6acfa..59c0112c696 100644
--- a/src/backend/utils/adt/amutils.c
+++ b/src/backend/utils/adt/amutils.c
@@ -156,7 +156,7 @@ indexam_property(FunctionCallInfo fcinfo,
 	bool		isnull = false;
 	int			natts = 0;
 	IndexAMProperty prop;
-	IndexAmRoutine *routine;
+	const IndexAmRoutine *routine;
 
 	/* Try to convert property name to enum (no error if not known) */
 	prop = lookup_prop_name(propname);
@@ -452,7 +452,7 @@ pg_indexam_progress_phasename(PG_FUNCTION_ARGS)
 {
 	Oid			amoid = PG_GETARG_OID(0);
 	int32		phasenum = PG_GETARG_INT32(1);
-	IndexAmRoutine *routine;
+	const IndexAmRoutine *routine;
 	char	   *name;
 
 	routine = GetIndexAmRoutineByAmId(amoid, true);
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 467b08198b8..a9a2184e90b 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -1281,7 +1281,7 @@ pg_get_indexdef_worker(Oid indexrelid, int colno,
 	Form_pg_index idxrec;
 	Form_pg_class idxrelrec;
 	Form_pg_am	amrec;
-	IndexAmRoutine *amroutine;
+	const IndexAmRoutine *amroutine;
 	List	   *indexprs;
 	ListCell   *indexpr_item;
 	List	   *context;
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index c460a72b75d..c927bef1224 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -232,10 +232,9 @@ get_opmethod_canorder(Oid amoid)
 		default:
 			{
 				bool		result;
-				IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
+				const IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
 
 				result = amroutine->amcanorder;
-				pfree(amroutine);
 				return result;
 			}
 	}
@@ -729,7 +728,7 @@ get_op_index_interpretation(Oid opno)
 			{
 				HeapTuple	op_tuple = &catlist->members[i]->tuple;
 				Form_pg_amop op_form = (Form_pg_amop) GETSTRUCT(op_tuple);
-				IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
+				const IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
 				CompareType cmptype;
 
 				/* must be ordering index */
@@ -803,7 +802,7 @@ equality_ops_are_compatible(Oid opno1, Oid opno2)
 		 */
 		if (op_in_opfamily(opno2, op_form->amopfamily))
 		{
-			IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
+			const IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
 
 			if (amroutine->amconsistentequality)
 			{
@@ -859,7 +858,7 @@ comparison_ops_are_compatible(Oid opno1, Oid opno2)
 		 */
 		if (op_in_opfamily(opno2, op_form->amopfamily))
 		{
-			IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
+			const IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
 
 			if (amroutine->amconsistentordering)
 			{
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 68ff67de549..efeb65115ed 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -1420,22 +1420,7 @@ RelationInitPhysicalAddr(Relation relation)
 static void
 InitIndexAmRoutine(Relation relation)
 {
-	IndexAmRoutine *cached,
-			   *tmp;
-
-	/*
-	 * Call the amhandler in current, short-lived memory context, just in case
-	 * it leaks anything (it probably won't, but let's be paranoid).
-	 */
-	tmp = GetIndexAmRoutine(relation->rd_amhandler);
-
-	/* OK, now transfer the data into relation's rd_indexcxt. */
-	cached = (IndexAmRoutine *) MemoryContextAlloc(relation->rd_indexcxt,
-												   sizeof(IndexAmRoutine));
-	memcpy(cached, tmp, sizeof(IndexAmRoutine));
-	relation->rd_indam = cached;
-
-	pfree(tmp);
+	relation->rd_indam = GetIndexAmRoutine(relation->rd_amhandler);
 }
 
 /*
diff --git a/src/include/access/amapi.h b/src/include/access/amapi.h
index 52916bab7a3..de934396fa2 100644
--- a/src/include/access/amapi.h
+++ b/src/include/access/amapi.h
@@ -324,8 +324,8 @@ typedef struct IndexAmRoutine
 
 
 /* Functions in access/index/amapi.c */
-extern IndexAmRoutine *GetIndexAmRoutine(Oid amhandler);
-extern IndexAmRoutine *GetIndexAmRoutineByAmId(Oid amoid, bool noerror);
+extern const IndexAmRoutine *GetIndexAmRoutine(Oid amhandler);
+extern const IndexAmRoutine *GetIndexAmRoutineByAmId(Oid amoid, bool noerror);
 extern CompareType IndexAmTranslateStrategy(StrategyNumber strategy, Oid amoid, Oid opfamily, bool missing_ok);
 extern StrategyNumber IndexAmTranslateCompareType(CompareType cmptype, Oid amoid, Oid opfamily, bool missing_ok);
 
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index b552359915f..87b776c98fe 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -203,7 +203,7 @@ typedef struct RelationData
 	 */
 	MemoryContext rd_indexcxt;	/* private memory cxt for this stuff */
 	/* use "struct" here to avoid needing to include amapi.h: */
-	struct IndexAmRoutine *rd_indam;	/* index AM's API struct */
+	const struct IndexAmRoutine *rd_indam;	/* index AM's API struct */
 	Oid		   *rd_opfamily;	/* OIDs of op families for each index col */
 	Oid		   *rd_opcintype;	/* OIDs of opclass declared input data types */
 	RegProcedure *rd_support;	/* OIDs of support procedures */
diff --git a/src/test/modules/dummy_index_am/dummy_index_am.c b/src/test/modules/dummy_index_am/dummy_index_am.c
index 94ef639b6fc..98a603892f4 100644
--- a/src/test/modules/dummy_index_am/dummy_index_am.c
+++ b/src/test/modules/dummy_index_am/dummy_index_am.c
@@ -276,56 +276,57 @@ diendscan(IndexScanDesc scan)
 Datum
 dihandler(PG_FUNCTION_ARGS)
 {
-	IndexAmRoutine *amroutine = makeNode(IndexAmRoutine);
-
-	amroutine->amstrategies = 0;
-	amroutine->amsupport = 1;
-	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
-	amroutine->amcanhash = false;
-	amroutine->amconsistentequality = false;
-	amroutine->amconsistentordering = 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->amcanbuildparallel = false;
-	amroutine->amcaninclude = false;
-	amroutine->amusemaintenanceworkmem = false;
-	amroutine->amsummarizing = false;
-	amroutine->amparallelvacuumoptions = VACUUM_OPTION_NO_PARALLEL;
-	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->amgettreeheight = NULL;
-	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);
+	static const IndexAmRoutine amroutine = {
+		.type = T_IndexAmRoutine,
+		.amstrategies = 0,
+		.amsupport = 1,
+		.amcanorder = false,
+		.amcanorderbyop = false,
+		.amcanhash = false,
+		.amconsistentequality = false,
+		.amconsistentordering = false,
+		.amcanbackward = false,
+		.amcanunique = false,
+		.amcanmulticol = false,
+		.amoptionalkey = false,
+		.amsearcharray = false,
+		.amsearchnulls = false,
+		.amstorage = false,
+		.amclusterable = false,
+		.ampredlocks = false,
+		.amcanparallel = false,
+		.amcanbuildparallel = false,
+		.amcaninclude = false,
+		.amusemaintenanceworkmem = false,
+		.amsummarizing = false,
+		.amparallelvacuumoptions = VACUUM_OPTION_NO_PARALLEL,
+		.amkeytype = InvalidOid,
+	
+		.ambuild = dibuild,
+		.ambuildempty = dibuildempty,
+		.aminsert = diinsert,
+		.ambulkdelete = dibulkdelete,
+		.amvacuumcleanup = divacuumcleanup,
+		.amcanreturn = NULL,
+		.amcostestimate = dicostestimate,
+		.amgettreeheight = NULL,
+		.amoptions = dioptions,
+		.amproperty = NULL,
+		.ambuildphasename = NULL,
+		.amvalidate = divalidate,
+		.ambeginscan = dibeginscan,
+		.amrescan = direscan,
+		.amgettuple = NULL,
+		.amgetbitmap = NULL,
+		.amendscan = diendscan,
+		.ammarkpos = NULL,
+		.amrestrpos = NULL,
+		.amestimateparallelscan = NULL,
+		.aminitparallelscan = NULL,
+		.amparallelrescan = NULL,
+	};
+
+	PG_RETURN_POINTER(&amroutine);
 }
 
 void
-- 
2.48.1