Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 2169 insertions, 0 deletions

diff --git a/src/backend/access/index/Makefile b/src/backend/access/index/Makefile
new file mode 100644
index 0000000..6f2e306
--- /dev/null
+++ b/src/backend/access/index/Makefile
@@ -0,0 +1,21 @@
+#-------------------------------------------------------------------------
+#
+# Makefile--
+#    Makefile for access/index
+#
+# IDENTIFICATION
+#    src/backend/access/index/Makefile
+#
+#-------------------------------------------------------------------------
+
+subdir = src/backend/access/index
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+
+OBJS = \
+	amapi.o \
+	amvalidate.o \
+	genam.o \
+	indexam.o
+
+include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/index/amapi.c b/src/backend/access/index/amapi.c
new file mode 100644
index 0000000..d30bc43
--- /dev/null
+++ b/src/backend/access/index/amapi.c
@@ -0,0 +1,143 @@
+/*-------------------------------------------------------------------------
+ *
+ * amapi.c
+ *	  Support routines for API for Postgres index access methods.
+ *
+ * Copyright (c) 2015-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/index/amapi.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/amapi.h"
+#include "access/htup_details.h"
+#include "catalog/pg_am.h"
+#include "catalog/pg_opclass.h"
+#include "utils/builtins.h"
+#include "utils/syscache.h"
+
+
+/*
+ * GetIndexAmRoutine - call the specified access method handler routine to get
+ * its IndexAmRoutine struct, which will be palloc'd in the caller's context.
+ *
+ * Note that if the amhandler function is built-in, this will not involve
+ * any catalog access.  It's therefore safe to use this while bootstrapping
+ * indexes for the system catalogs.  relcache.c relies on that.
+ */
+IndexAmRoutine *
+GetIndexAmRoutine(Oid amhandler)
+{
+	Datum		datum;
+	IndexAmRoutine *routine;
+
+	datum = OidFunctionCall0(amhandler);
+	routine = (IndexAmRoutine *) DatumGetPointer(datum);
+
+	if (routine == NULL || !IsA(routine, IndexAmRoutine))
+		elog(ERROR, "index access method handler function %u did not return an IndexAmRoutine struct",
+			 amhandler);
+
+	return routine;
+}
+
+/*
+ * GetIndexAmRoutineByAmId - look up the handler of the index access method
+ * with the given OID, and get its IndexAmRoutine struct.
+ *
+ * If the given OID isn't a valid index access method, returns NULL if
+ * noerror is true, else throws error.
+ */
+IndexAmRoutine *
+GetIndexAmRoutineByAmId(Oid amoid, bool noerror)
+{
+	HeapTuple	tuple;
+	Form_pg_am	amform;
+	regproc		amhandler;
+
+	/* Get handler function OID for the access method */
+	tuple = SearchSysCache1(AMOID, ObjectIdGetDatum(amoid));
+	if (!HeapTupleIsValid(tuple))
+	{
+		if (noerror)
+			return NULL;
+		elog(ERROR, "cache lookup failed for access method %u",
+			 amoid);
+	}
+	amform = (Form_pg_am) GETSTRUCT(tuple);
+
+	/* Check if it's an index access method as opposed to some other AM */
+	if (amform->amtype != AMTYPE_INDEX)
+	{
+		if (noerror)
+		{
+			ReleaseSysCache(tuple);
+			return NULL;
+		}
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("access method \"%s\" is not of type %s",
+						NameStr(amform->amname), "INDEX")));
+	}
+
+	amhandler = amform->amhandler;
+
+	/* Complain if handler OID is invalid */
+	if (!RegProcedureIsValid(amhandler))
+	{
+		if (noerror)
+		{
+			ReleaseSysCache(tuple);
+			return NULL;
+		}
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("index access method \"%s\" does not have a handler",
+						NameStr(amform->amname))));
+	}
+
+	ReleaseSysCache(tuple);
+
+	/* And finally, call the handler function to get the API struct. */
+	return GetIndexAmRoutine(amhandler);
+}
+
+
+/*
+ * Ask appropriate access method to validate the specified opclass.
+ */
+Datum
+amvalidate(PG_FUNCTION_ARGS)
+{
+	Oid			opclassoid = PG_GETARG_OID(0);
+	bool		result;
+	HeapTuple	classtup;
+	Form_pg_opclass classform;
+	Oid			amoid;
+	IndexAmRoutine *amroutine;
+
+	classtup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclassoid));
+	if (!HeapTupleIsValid(classtup))
+		elog(ERROR, "cache lookup failed for operator class %u", opclassoid);
+	classform = (Form_pg_opclass) GETSTRUCT(classtup);
+
+	amoid = classform->opcmethod;
+
+	ReleaseSysCache(classtup);
+
+	amroutine = GetIndexAmRoutineByAmId(amoid, false);
+
+	if (amroutine->amvalidate == NULL)
+		elog(ERROR, "function amvalidate is not defined for index access method %u",
+			 amoid);
+
+	result = amroutine->amvalidate(opclassoid);
+
+	pfree(amroutine);
+
+	PG_RETURN_BOOL(result);
+}
diff --git a/src/backend/access/index/amvalidate.c b/src/backend/access/index/amvalidate.c
new file mode 100644
index 0000000..9dd0ae6
--- /dev/null
+++ b/src/backend/access/index/amvalidate.c
@@ -0,0 +1,276 @@
+/*-------------------------------------------------------------------------
+ *
+ * amvalidate.c
+ *	  Support routines for index access methods' amvalidate and
+ *	  amadjustmembers functions.
+ *
+ * Copyright (c) 2016-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/index/amvalidate.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/amvalidate.h"
+#include "access/htup_details.h"
+#include "catalog/pg_am.h"
+#include "catalog/pg_amop.h"
+#include "catalog/pg_amproc.h"
+#include "catalog/pg_opclass.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
+#include "parser/parse_coerce.h"
+#include "utils/syscache.h"
+
+
+/*
+ * identify_opfamily_groups() returns a List of OpFamilyOpFuncGroup structs,
+ * one for each combination of lefttype/righttype present in the family's
+ * operator and support function lists.  If amopstrategy K is present for
+ * this datatype combination, we set bit 1 << K in operatorset, and similarly
+ * for the support functions.  With uint64 fields we can handle operator and
+ * function numbers up to 63, which is plenty for the foreseeable future.
+ *
+ * The given CatCLists are expected to represent a single opfamily fetched
+ * from the AMOPSTRATEGY and AMPROCNUM caches, so that they will be in
+ * order by those caches' second and third cache keys, namely the datatypes.
+ */
+List *
+identify_opfamily_groups(CatCList *oprlist, CatCList *proclist)
+{
+	List	   *result = NIL;
+	OpFamilyOpFuncGroup *thisgroup;
+	Form_pg_amop oprform;
+	Form_pg_amproc procform;
+	int			io,
+				ip;
+
+	/* We need the lists to be ordered; should be true in normal operation */
+	if (!oprlist->ordered || !proclist->ordered)
+		elog(ERROR, "cannot validate operator family without ordered data");
+
+	/*
+	 * Advance through the lists concurrently.  Thanks to the ordering, we
+	 * should see all operators and functions of a given datatype pair
+	 * consecutively.
+	 */
+	thisgroup = NULL;
+	io = ip = 0;
+	if (io < oprlist->n_members)
+	{
+		oprform = (Form_pg_amop) GETSTRUCT(&oprlist->members[io]->tuple);
+		io++;
+	}
+	else
+		oprform = NULL;
+	if (ip < proclist->n_members)
+	{
+		procform = (Form_pg_amproc) GETSTRUCT(&proclist->members[ip]->tuple);
+		ip++;
+	}
+	else
+		procform = NULL;
+
+	while (oprform || procform)
+	{
+		if (oprform && thisgroup &&
+			oprform->amoplefttype == thisgroup->lefttype &&
+			oprform->amoprighttype == thisgroup->righttype)
+		{
+			/* Operator belongs to current group; include it and advance */
+
+			/* Ignore strategy numbers outside supported range */
+			if (oprform->amopstrategy > 0 && oprform->amopstrategy < 64)
+				thisgroup->operatorset |= ((uint64) 1) << oprform->amopstrategy;
+
+			if (io < oprlist->n_members)
+			{
+				oprform = (Form_pg_amop) GETSTRUCT(&oprlist->members[io]->tuple);
+				io++;
+			}
+			else
+				oprform = NULL;
+			continue;
+		}
+
+		if (procform && thisgroup &&
+			procform->amproclefttype == thisgroup->lefttype &&
+			procform->amprocrighttype == thisgroup->righttype)
+		{
+			/* Procedure belongs to current group; include it and advance */
+
+			/* Ignore function numbers outside supported range */
+			if (procform->amprocnum > 0 && procform->amprocnum < 64)
+				thisgroup->functionset |= ((uint64) 1) << procform->amprocnum;
+
+			if (ip < proclist->n_members)
+			{
+				procform = (Form_pg_amproc) GETSTRUCT(&proclist->members[ip]->tuple);
+				ip++;
+			}
+			else
+				procform = NULL;
+			continue;
+		}
+
+		/* Time for a new group */
+		thisgroup = (OpFamilyOpFuncGroup *) palloc(sizeof(OpFamilyOpFuncGroup));
+		if (oprform &&
+			(!procform ||
+			 (oprform->amoplefttype < procform->amproclefttype ||
+			  (oprform->amoplefttype == procform->amproclefttype &&
+			   oprform->amoprighttype < procform->amprocrighttype))))
+		{
+			thisgroup->lefttype = oprform->amoplefttype;
+			thisgroup->righttype = oprform->amoprighttype;
+		}
+		else
+		{
+			thisgroup->lefttype = procform->amproclefttype;
+			thisgroup->righttype = procform->amprocrighttype;
+		}
+		thisgroup->operatorset = thisgroup->functionset = 0;
+		result = lappend(result, thisgroup);
+	}
+
+	return result;
+}
+
+/*
+ * Validate the signature (argument and result types) of an opclass support
+ * function.  Return true if OK, false if not.
+ *
+ * The "..." represents maxargs argument-type OIDs.  If "exact" is true, they
+ * must match the function arg types exactly, else only binary-coercibly.
+ * In any case the function result type must match restype exactly.
+ */
+bool
+check_amproc_signature(Oid funcid, Oid restype, bool exact,
+					   int minargs, int maxargs,...)
+{
+	bool		result = true;
+	HeapTuple	tp;
+	Form_pg_proc procform;
+	va_list		ap;
+	int			i;
+
+	tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for function %u", funcid);
+	procform = (Form_pg_proc) GETSTRUCT(tp);
+
+	if (procform->prorettype != restype || procform->proretset ||
+		procform->pronargs < minargs || procform->pronargs > maxargs)
+		result = false;
+
+	va_start(ap, maxargs);
+	for (i = 0; i < maxargs; i++)
+	{
+		Oid			argtype = va_arg(ap, Oid);
+
+		if (i >= procform->pronargs)
+			continue;
+		if (exact ? (argtype != procform->proargtypes.values[i]) :
+			!IsBinaryCoercible(argtype, procform->proargtypes.values[i]))
+			result = false;
+	}
+	va_end(ap);
+
+	ReleaseSysCache(tp);
+	return result;
+}
+
+/*
+ * Validate the signature of an opclass options support function, that should
+ * be 'void(internal)'.
+ */
+bool
+check_amoptsproc_signature(Oid funcid)
+{
+	return check_amproc_signature(funcid, VOIDOID, true, 1, 1, INTERNALOID);
+}
+
+/*
+ * Validate the signature (argument and result types) of an opclass operator.
+ * Return true if OK, false if not.
+ *
+ * Currently, we can hard-wire this as accepting only binary operators.  Also,
+ * we can insist on exact type matches, since the given lefttype/righttype
+ * come from pg_amop and should always match the operator exactly.
+ */
+bool
+check_amop_signature(Oid opno, Oid restype, Oid lefttype, Oid righttype)
+{
+	bool		result = true;
+	HeapTuple	tp;
+	Form_pg_operator opform;
+
+	tp = SearchSysCache1(OPEROID, ObjectIdGetDatum(opno));
+	if (!HeapTupleIsValid(tp))	/* shouldn't happen */
+		elog(ERROR, "cache lookup failed for operator %u", opno);
+	opform = (Form_pg_operator) GETSTRUCT(tp);
+
+	if (opform->oprresult != restype || opform->oprkind != 'b' ||
+		opform->oprleft != lefttype || opform->oprright != righttype)
+		result = false;
+
+	ReleaseSysCache(tp);
+	return result;
+}
+
+/*
+ * Get the OID of the opclass belonging to an opfamily and accepting
+ * the specified type as input type.  Returns InvalidOid if no such opclass.
+ *
+ * If there is more than one such opclass, you get a random one of them.
+ * Since that shouldn't happen, we don't waste cycles checking.
+ *
+ * We could look up the AM's OID from the opfamily, but all existing callers
+ * know that or can get it without an extra lookup, so we make them pass it.
+ */
+Oid
+opclass_for_family_datatype(Oid amoid, Oid opfamilyoid, Oid datatypeoid)
+{
+	Oid			result = InvalidOid;
+	CatCList   *opclist;
+	int			i;
+
+	/*
+	 * We search through all the AM's opclasses to see if one matches.  This
+	 * is a bit inefficient but there is no better index available.  It also
+	 * saves making an explicit check that the opfamily belongs to the AM.
+	 */
+	opclist = SearchSysCacheList1(CLAAMNAMENSP, ObjectIdGetDatum(amoid));
+
+	for (i = 0; i < opclist->n_members; i++)
+	{
+		HeapTuple	classtup = &opclist->members[i]->tuple;
+		Form_pg_opclass classform = (Form_pg_opclass) GETSTRUCT(classtup);
+
+		if (classform->opcfamily == opfamilyoid &&
+			classform->opcintype == datatypeoid)
+		{
+			result = classform->oid;
+			break;
+		}
+	}
+
+	ReleaseCatCacheList(opclist);
+
+	return result;
+}
+
+/*
+ * Is the datatype a legitimate input type for the btree opfamily?
+ */
+bool
+opfamily_can_sort_type(Oid opfamilyoid, Oid datatypeoid)
+{
+	return OidIsValid(opclass_for_family_datatype(BTREE_AM_OID,
+												  opfamilyoid,
+												  datatypeoid));
+}
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
new file mode 100644
index 0000000..b93288a
--- /dev/null
+++ b/src/backend/access/index/genam.c
@@ -0,0 +1,745 @@
+/*-------------------------------------------------------------------------
+ *
+ * genam.c
+ *	  general index access method routines
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/index/genam.c
+ *
+ * NOTES
+ *	  many of the old access method routines have been turned into
+ *	  macros and moved to genam.h -cim 4/30/91
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/relscan.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "catalog/index.h"
+#include "lib/stringinfo.h"
+#include "miscadmin.h"
+#include "storage/bufmgr.h"
+#include "storage/procarray.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/rls.h"
+#include "utils/ruleutils.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+
+
+/* ----------------------------------------------------------------
+ *		general access method routines
+ *
+ *		All indexed access methods use an identical scan structure.
+ *		We don't know how the various AMs do locking, however, so we don't
+ *		do anything about that here.
+ *
+ *		The intent is that an AM implementor will define a beginscan routine
+ *		that calls RelationGetIndexScan, to fill in the scan, and then does
+ *		whatever kind of locking he wants.
+ *
+ *		At the end of a scan, the AM's endscan routine undoes the locking,
+ *		but does *not* call IndexScanEnd --- the higher-level index_endscan
+ *		routine does that.  (We can't do it in the AM because index_endscan
+ *		still needs to touch the IndexScanDesc after calling the AM.)
+ *
+ *		Because of this, the AM does not have a choice whether to call
+ *		RelationGetIndexScan or not; its beginscan routine must return an
+ *		object made by RelationGetIndexScan.  This is kinda ugly but not
+ *		worth cleaning up now.
+ * ----------------------------------------------------------------
+ */
+
+/* ----------------
+ *	RelationGetIndexScan -- Create and fill an IndexScanDesc.
+ *
+ *		This routine creates an index scan structure and sets up initial
+ *		contents for it.
+ *
+ *		Parameters:
+ *				indexRelation -- index relation for scan.
+ *				nkeys -- count of scan keys (index qual conditions).
+ *				norderbys -- count of index order-by operators.
+ *
+ *		Returns:
+ *				An initialized IndexScanDesc.
+ * ----------------
+ */
+IndexScanDesc
+RelationGetIndexScan(Relation indexRelation, int nkeys, int norderbys)
+{
+	IndexScanDesc scan;
+
+	scan = (IndexScanDesc) palloc(sizeof(IndexScanDescData));
+
+	scan->heapRelation = NULL;	/* may be set later */
+	scan->xs_heapfetch = NULL;
+	scan->indexRelation = indexRelation;
+	scan->xs_snapshot = InvalidSnapshot;	/* caller must initialize this */
+	scan->numberOfKeys = nkeys;
+	scan->numberOfOrderBys = norderbys;
+
+	/*
+	 * We allocate key workspace here, but it won't get filled until amrescan.
+	 */
+	if (nkeys > 0)
+		scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys);
+	else
+		scan->keyData = NULL;
+	if (norderbys > 0)
+		scan->orderByData = (ScanKey) palloc(sizeof(ScanKeyData) * norderbys);
+	else
+		scan->orderByData = NULL;
+
+	scan->xs_want_itup = false; /* may be set later */
+
+	/*
+	 * During recovery we ignore killed tuples and don't bother to kill them
+	 * either. We do this because the xmin on the primary node could easily be
+	 * later than the xmin on the standby node, so that what the primary
+	 * thinks is killed is supposed to be visible on standby. So for correct
+	 * MVCC for queries during recovery we must ignore these hints and check
+	 * all tuples. Do *not* set ignore_killed_tuples to true when running in a
+	 * transaction that was started during recovery. xactStartedInRecovery
+	 * should not be altered by index AMs.
+	 */
+	scan->kill_prior_tuple = false;
+	scan->xactStartedInRecovery = TransactionStartedDuringRecovery();
+	scan->ignore_killed_tuples = !scan->xactStartedInRecovery;
+
+	scan->opaque = NULL;
+
+	scan->xs_itup = NULL;
+	scan->xs_itupdesc = NULL;
+	scan->xs_hitup = NULL;
+	scan->xs_hitupdesc = NULL;
+
+	return scan;
+}
+
+/* ----------------
+ *	IndexScanEnd -- End an index scan.
+ *
+ *		This routine just releases the storage acquired by
+ *		RelationGetIndexScan().  Any AM-level resources are
+ *		assumed to already have been released by the AM's
+ *		endscan routine.
+ *
+ *	Returns:
+ *		None.
+ * ----------------
+ */
+void
+IndexScanEnd(IndexScanDesc scan)
+{
+	if (scan->keyData != NULL)
+		pfree(scan->keyData);
+	if (scan->orderByData != NULL)
+		pfree(scan->orderByData);
+
+	pfree(scan);
+}
+
+/*
+ * BuildIndexValueDescription
+ *
+ * Construct a string describing the contents of an index entry, in the
+ * form "(key_name, ...)=(key_value, ...)".  This is currently used
+ * for building unique-constraint and exclusion-constraint error messages,
+ * so only key columns of the index are checked and printed.
+ *
+ * Note that if the user does not have permissions to view all of the
+ * columns involved then a NULL is returned.  Returning a partial key seems
+ * unlikely to be useful and we have no way to know which of the columns the
+ * user provided (unlike in ExecBuildSlotValueDescription).
+ *
+ * The passed-in values/nulls arrays are the "raw" input to the index AM,
+ * e.g. results of FormIndexDatum --- this is not necessarily what is stored
+ * in the index, but it's what the user perceives to be stored.
+ *
+ * Note: if you change anything here, check whether
+ * ExecBuildSlotPartitionKeyDescription() in execMain.c needs a similar
+ * change.
+ */
+char *
+BuildIndexValueDescription(Relation indexRelation,
+						   Datum *values, bool *isnull)
+{
+	StringInfoData buf;
+	Form_pg_index idxrec;
+	int			indnkeyatts;
+	int			i;
+	int			keyno;
+	Oid			indexrelid = RelationGetRelid(indexRelation);
+	Oid			indrelid;
+	AclResult	aclresult;
+
+	indnkeyatts = IndexRelationGetNumberOfKeyAttributes(indexRelation);
+
+	/*
+	 * Check permissions- if the user does not have access to view all of the
+	 * key columns then return NULL to avoid leaking data.
+	 *
+	 * First check if RLS is enabled for the relation.  If so, return NULL to
+	 * avoid leaking data.
+	 *
+	 * Next we need to check table-level SELECT access and then, if there is
+	 * no access there, check column-level permissions.
+	 */
+	idxrec = indexRelation->rd_index;
+	indrelid = idxrec->indrelid;
+	Assert(indexrelid == idxrec->indexrelid);
+
+	/* RLS check- if RLS is enabled then we don't return anything. */
+	if (check_enable_rls(indrelid, InvalidOid, true) == RLS_ENABLED)
+		return NULL;
+
+	/* Table-level SELECT is enough, if the user has it */
+	aclresult = pg_class_aclcheck(indrelid, GetUserId(), ACL_SELECT);
+	if (aclresult != ACLCHECK_OK)
+	{
+		/*
+		 * No table-level access, so step through the columns in the index and
+		 * make sure the user has SELECT rights on all of them.
+		 */
+		for (keyno = 0; keyno < indnkeyatts; keyno++)
+		{
+			AttrNumber	attnum = idxrec->indkey.values[keyno];
+
+			/*
+			 * Note that if attnum == InvalidAttrNumber, then this is an index
+			 * based on an expression and we return no detail rather than try
+			 * to figure out what column(s) the expression includes and if the
+			 * user has SELECT rights on them.
+			 */
+			if (attnum == InvalidAttrNumber ||
+				pg_attribute_aclcheck(indrelid, attnum, GetUserId(),
+									  ACL_SELECT) != ACLCHECK_OK)
+			{
+				/* No access, so clean up and return */
+				return NULL;
+			}
+		}
+	}
+
+	initStringInfo(&buf);
+	appendStringInfo(&buf, "(%s)=(",
+					 pg_get_indexdef_columns(indexrelid, true));
+
+	for (i = 0; i < indnkeyatts; i++)
+	{
+		char	   *val;
+
+		if (isnull[i])
+			val = "null";
+		else
+		{
+			Oid			foutoid;
+			bool		typisvarlena;
+
+			/*
+			 * The provided data is not necessarily of the type stored in the
+			 * index; rather it is of the index opclass's input type. So look
+			 * at rd_opcintype not the index tupdesc.
+			 *
+			 * Note: this is a bit shaky for opclasses that have pseudotype
+			 * input types such as ANYARRAY or RECORD.  Currently, the
+			 * typoutput functions associated with the pseudotypes will work
+			 * okay, but we might have to try harder in future.
+			 */
+			getTypeOutputInfo(indexRelation->rd_opcintype[i],
+							  &foutoid, &typisvarlena);
+			val = OidOutputFunctionCall(foutoid, values[i]);
+		}
+
+		if (i > 0)
+			appendStringInfoString(&buf, ", ");
+		appendStringInfoString(&buf, val);
+	}
+
+	appendStringInfoChar(&buf, ')');
+
+	return buf.data;
+}
+
+/*
+ * Get the latestRemovedXid from the table entries pointed at by the index
+ * tuples being deleted using an AM-generic approach.
+ *
+ * This is a table_index_delete_tuples() shim used by index AMs that have
+ * simple requirements.  These callers only need to consult the tableam to get
+ * a latestRemovedXid value, and only expect to delete tuples that are already
+ * known deletable.  When a latestRemovedXid value isn't needed in index AM's
+ * deletion WAL record, it is safe for it to skip calling here entirely.
+ *
+ * We assume that caller index AM uses the standard IndexTuple representation,
+ * with table TIDs stored in the t_tid field.  We also expect (and assert)
+ * that the line pointers on page for 'itemnos' offsets are already marked
+ * LP_DEAD.
+ */
+TransactionId
+index_compute_xid_horizon_for_tuples(Relation irel,
+									 Relation hrel,
+									 Buffer ibuf,
+									 OffsetNumber *itemnos,
+									 int nitems)
+{
+	TM_IndexDeleteOp delstate;
+	TransactionId latestRemovedXid = InvalidTransactionId;
+	Page		ipage = BufferGetPage(ibuf);
+	IndexTuple	itup;
+
+	Assert(nitems > 0);
+
+	delstate.bottomup = false;
+	delstate.bottomupfreespace = 0;
+	delstate.ndeltids = 0;
+	delstate.deltids = palloc(nitems * sizeof(TM_IndexDelete));
+	delstate.status = palloc(nitems * sizeof(TM_IndexStatus));
+
+	/* identify what the index tuples about to be deleted point to */
+	for (int i = 0; i < nitems; i++)
+	{
+		ItemId		iitemid;
+
+		iitemid = PageGetItemId(ipage, itemnos[i]);
+		itup = (IndexTuple) PageGetItem(ipage, iitemid);
+
+		Assert(ItemIdIsDead(iitemid));
+
+		ItemPointerCopy(&itup->t_tid, &delstate.deltids[i].tid);
+		delstate.deltids[i].id = delstate.ndeltids;
+		delstate.status[i].idxoffnum = InvalidOffsetNumber; /* unused */
+		delstate.status[i].knowndeletable = true;	/* LP_DEAD-marked */
+		delstate.status[i].promising = false;	/* unused */
+		delstate.status[i].freespace = 0;	/* unused */
+
+		delstate.ndeltids++;
+	}
+
+	/* determine the actual xid horizon */
+	latestRemovedXid = table_index_delete_tuples(hrel, &delstate);
+
+	/* assert tableam agrees that all items are deletable */
+	Assert(delstate.ndeltids == nitems);
+
+	pfree(delstate.deltids);
+	pfree(delstate.status);
+
+	return latestRemovedXid;
+}
+
+
+/* ----------------------------------------------------------------
+ *		heap-or-index-scan access to system catalogs
+ *
+ *		These functions support system catalog accesses that normally use
+ *		an index but need to be capable of being switched to heap scans
+ *		if the system indexes are unavailable.
+ *
+ *		The specified scan keys must be compatible with the named index.
+ *		Generally this means that they must constrain either all columns
+ *		of the index, or the first K columns of an N-column index.
+ *
+ *		These routines could work with non-system tables, actually,
+ *		but they're only useful when there is a known index to use with
+ *		the given scan keys; so in practice they're only good for
+ *		predetermined types of scans of system catalogs.
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * systable_beginscan --- set up for heap-or-index scan
+ *
+ *	rel: catalog to scan, already opened and suitably locked
+ *	indexId: OID of index to conditionally use
+ *	indexOK: if false, forces a heap scan (see notes below)
+ *	snapshot: time qual to use (NULL for a recent catalog snapshot)
+ *	nkeys, key: scan keys
+ *
+ * The attribute numbers in the scan key should be set for the heap case.
+ * If we choose to index, we reset them to 1..n to reference the index
+ * columns.  Note this means there must be one scankey qualification per
+ * index column!  This is checked by the Asserts in the normal, index-using
+ * case, but won't be checked if the heapscan path is taken.
+ *
+ * The routine checks the normal cases for whether an indexscan is safe,
+ * but caller can make additional checks and pass indexOK=false if needed.
+ * In standard case indexOK can simply be constant TRUE.
+ */
+SysScanDesc
+systable_beginscan(Relation heapRelation,
+				   Oid indexId,
+				   bool indexOK,
+				   Snapshot snapshot,
+				   int nkeys, ScanKey key)
+{
+	SysScanDesc sysscan;
+	Relation	irel;
+
+	if (indexOK &&
+		!IgnoreSystemIndexes &&
+		!ReindexIsProcessingIndex(indexId))
+		irel = index_open(indexId, AccessShareLock);
+	else
+		irel = NULL;
+
+	sysscan = (SysScanDesc) palloc(sizeof(SysScanDescData));
+
+	sysscan->heap_rel = heapRelation;
+	sysscan->irel = irel;
+	sysscan->slot = table_slot_create(heapRelation, NULL);
+
+	if (snapshot == NULL)
+	{
+		Oid			relid = RelationGetRelid(heapRelation);
+
+		snapshot = RegisterSnapshot(GetCatalogSnapshot(relid));
+		sysscan->snapshot = snapshot;
+	}
+	else
+	{
+		/* Caller is responsible for any snapshot. */
+		sysscan->snapshot = NULL;
+	}
+
+	if (irel)
+	{
+		int			i;
+
+		/* Change attribute numbers to be index column numbers. */
+		for (i = 0; i < nkeys; i++)
+		{
+			int			j;
+
+			for (j = 0; j < IndexRelationGetNumberOfAttributes(irel); j++)
+			{
+				if (key[i].sk_attno == irel->rd_index->indkey.values[j])
+				{
+					key[i].sk_attno = j + 1;
+					break;
+				}
+			}
+			if (j == IndexRelationGetNumberOfAttributes(irel))
+				elog(ERROR, "column is not in index");
+		}
+
+		sysscan->iscan = index_beginscan(heapRelation, irel,
+										 snapshot, nkeys, 0);
+		index_rescan(sysscan->iscan, key, nkeys, NULL, 0);
+		sysscan->scan = NULL;
+	}
+	else
+	{
+		/*
+		 * We disallow synchronized scans when forced to use a heapscan on a
+		 * catalog.  In most cases the desired rows are near the front, so
+		 * that the unpredictable start point of a syncscan is a serious
+		 * disadvantage; and there are no compensating advantages, because
+		 * it's unlikely that such scans will occur in parallel.
+		 */
+		sysscan->scan = table_beginscan_strat(heapRelation, snapshot,
+											  nkeys, key,
+											  true, false);
+		sysscan->iscan = NULL;
+	}
+
+	/*
+	 * If CheckXidAlive is set then set a flag to indicate that system table
+	 * scan is in-progress.  See detailed comments in xact.c where these
+	 * variables are declared.
+	 */
+	if (TransactionIdIsValid(CheckXidAlive))
+		bsysscan = true;
+
+	return sysscan;
+}
+
+/*
+ * HandleConcurrentAbort - Handle concurrent abort of the CheckXidAlive.
+ *
+ * Error out, if CheckXidAlive is aborted. We can't directly use
+ * TransactionIdDidAbort as after crash such transaction might not have been
+ * marked as aborted.  See detailed comments in xact.c where the variable
+ * is declared.
+ */
+static inline void
+HandleConcurrentAbort()
+{
+	if (TransactionIdIsValid(CheckXidAlive) &&
+		!TransactionIdIsInProgress(CheckXidAlive) &&
+		!TransactionIdDidCommit(CheckXidAlive))
+		ereport(ERROR,
+				(errcode(ERRCODE_TRANSACTION_ROLLBACK),
+				 errmsg("transaction aborted during system catalog scan")));
+}
+
+/*
+ * systable_getnext --- get next tuple in a heap-or-index scan
+ *
+ * Returns NULL if no more tuples available.
+ *
+ * Note that returned tuple is a reference to data in a disk buffer;
+ * it must not be modified, and should be presumed inaccessible after
+ * next getnext() or endscan() call.
+ *
+ * XXX: It'd probably make sense to offer a slot based interface, at least
+ * optionally.
+ */
+HeapTuple
+systable_getnext(SysScanDesc sysscan)
+{
+	HeapTuple	htup = NULL;
+
+	if (sysscan->irel)
+	{
+		if (index_getnext_slot(sysscan->iscan, ForwardScanDirection, sysscan->slot))
+		{
+			bool		shouldFree;
+
+			htup = ExecFetchSlotHeapTuple(sysscan->slot, false, &shouldFree);
+			Assert(!shouldFree);
+
+			/*
+			 * We currently don't need to support lossy index operators for
+			 * any system catalog scan.  It could be done here, using the scan
+			 * keys to drive the operator calls, if we arranged to save the
+			 * heap attnums during systable_beginscan(); this is practical
+			 * because we still wouldn't need to support indexes on
+			 * expressions.
+			 */
+			if (sysscan->iscan->xs_recheck)
+				elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+		}
+	}
+	else
+	{
+		if (table_scan_getnextslot(sysscan->scan, ForwardScanDirection, sysscan->slot))
+		{
+			bool		shouldFree;
+
+			htup = ExecFetchSlotHeapTuple(sysscan->slot, false, &shouldFree);
+			Assert(!shouldFree);
+		}
+	}
+
+	/*
+	 * Handle the concurrent abort while fetching the catalog tuple during
+	 * logical streaming of a transaction.
+	 */
+	HandleConcurrentAbort();
+
+	return htup;
+}
+
+/*
+ * systable_recheck_tuple --- recheck visibility of most-recently-fetched tuple
+ *
+ * In particular, determine if this tuple would be visible to a catalog scan
+ * that started now.  We don't handle the case of a non-MVCC scan snapshot,
+ * because no caller needs that yet.
+ *
+ * This is useful to test whether an object was deleted while we waited to
+ * acquire lock on it.
+ *
+ * Note: we don't actually *need* the tuple to be passed in, but it's a
+ * good crosscheck that the caller is interested in the right tuple.
+ */
+bool
+systable_recheck_tuple(SysScanDesc sysscan, HeapTuple tup)
+{
+	Snapshot	freshsnap;
+	bool		result;
+
+	Assert(tup == ExecFetchSlotHeapTuple(sysscan->slot, false, NULL));
+
+	/*
+	 * Trust that table_tuple_satisfies_snapshot() and its subsidiaries
+	 * (commonly LockBuffer() and HeapTupleSatisfiesMVCC()) do not themselves
+	 * acquire snapshots, so we need not register the snapshot.  Those
+	 * facilities are too low-level to have any business scanning tables.
+	 */
+	freshsnap = GetCatalogSnapshot(RelationGetRelid(sysscan->heap_rel));
+
+	result = table_tuple_satisfies_snapshot(sysscan->heap_rel,
+											sysscan->slot,
+											freshsnap);
+
+	/*
+	 * Handle the concurrent abort while fetching the catalog tuple during
+	 * logical streaming of a transaction.
+	 */
+	HandleConcurrentAbort();
+
+	return result;
+}
+
+/*
+ * systable_endscan --- close scan, release resources
+ *
+ * Note that it's still up to the caller to close the heap relation.
+ */
+void
+systable_endscan(SysScanDesc sysscan)
+{
+	if (sysscan->slot)
+	{
+		ExecDropSingleTupleTableSlot(sysscan->slot);
+		sysscan->slot = NULL;
+	}
+
+	if (sysscan->irel)
+	{
+		index_endscan(sysscan->iscan);
+		index_close(sysscan->irel, AccessShareLock);
+	}
+	else
+		table_endscan(sysscan->scan);
+
+	if (sysscan->snapshot)
+		UnregisterSnapshot(sysscan->snapshot);
+
+	/*
+	 * Reset the bsysscan flag at the end of the systable scan.  See detailed
+	 * comments in xact.c where these variables are declared.
+	 */
+	if (TransactionIdIsValid(CheckXidAlive))
+		bsysscan = false;
+
+	pfree(sysscan);
+}
+
+
+/*
+ * systable_beginscan_ordered --- set up for ordered catalog scan
+ *
+ * These routines have essentially the same API as systable_beginscan etc,
+ * except that they guarantee to return multiple matching tuples in
+ * index order.  Also, for largely historical reasons, the index to use
+ * is opened and locked by the caller, not here.
+ *
+ * Currently we do not support non-index-based scans here.  (In principle
+ * we could do a heapscan and sort, but the uses are in places that
+ * probably don't need to still work with corrupted catalog indexes.)
+ * For the moment, therefore, these functions are merely the thinest of
+ * wrappers around index_beginscan/index_getnext_slot.  The main reason for
+ * their existence is to centralize possible future support of lossy operators
+ * in catalog scans.
+ */
+SysScanDesc
+systable_beginscan_ordered(Relation heapRelation,
+						   Relation indexRelation,
+						   Snapshot snapshot,
+						   int nkeys, ScanKey key)
+{
+	SysScanDesc sysscan;
+	int			i;
+
+	/* REINDEX can probably be a hard error here ... */
+	if (ReindexIsProcessingIndex(RelationGetRelid(indexRelation)))
+		elog(ERROR, "cannot do ordered scan on index \"%s\", because it is being reindexed",
+			 RelationGetRelationName(indexRelation));
+	/* ... but we only throw a warning about violating IgnoreSystemIndexes */
+	if (IgnoreSystemIndexes)
+		elog(WARNING, "using index \"%s\" despite IgnoreSystemIndexes",
+			 RelationGetRelationName(indexRelation));
+
+	sysscan = (SysScanDesc) palloc(sizeof(SysScanDescData));
+
+	sysscan->heap_rel = heapRelation;
+	sysscan->irel = indexRelation;
+	sysscan->slot = table_slot_create(heapRelation, NULL);
+
+	if (snapshot == NULL)
+	{
+		Oid			relid = RelationGetRelid(heapRelation);
+
+		snapshot = RegisterSnapshot(GetCatalogSnapshot(relid));
+		sysscan->snapshot = snapshot;
+	}
+	else
+	{
+		/* Caller is responsible for any snapshot. */
+		sysscan->snapshot = NULL;
+	}
+
+	/* Change attribute numbers to be index column numbers. */
+	for (i = 0; i < nkeys; i++)
+	{
+		int			j;
+
+		for (j = 0; j < IndexRelationGetNumberOfAttributes(indexRelation); j++)
+		{
+			if (key[i].sk_attno == indexRelation->rd_index->indkey.values[j])
+			{
+				key[i].sk_attno = j + 1;
+				break;
+			}
+		}
+		if (j == IndexRelationGetNumberOfAttributes(indexRelation))
+			elog(ERROR, "column is not in index");
+	}
+
+	sysscan->iscan = index_beginscan(heapRelation, indexRelation,
+									 snapshot, nkeys, 0);
+	index_rescan(sysscan->iscan, key, nkeys, NULL, 0);
+	sysscan->scan = NULL;
+
+	return sysscan;
+}
+
+/*
+ * systable_getnext_ordered --- get next tuple in an ordered catalog scan
+ */
+HeapTuple
+systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	HeapTuple	htup = NULL;
+
+	Assert(sysscan->irel);
+	if (index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		htup = ExecFetchSlotHeapTuple(sysscan->slot, false, NULL);
+
+	/* See notes in systable_getnext */
+	if (htup && sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	/*
+	 * Handle the concurrent abort while fetching the catalog tuple during
+	 * logical streaming of a transaction.
+	 */
+	HandleConcurrentAbort();
+
+	return htup;
+}
+
+/*
+ * systable_endscan_ordered --- close scan, release resources
+ */
+void
+systable_endscan_ordered(SysScanDesc sysscan)
+{
+	if (sysscan->slot)
+	{
+		ExecDropSingleTupleTableSlot(sysscan->slot);
+		sysscan->slot = NULL;
+	}
+
+	Assert(sysscan->irel);
+	index_endscan(sysscan->iscan);
+	if (sysscan->snapshot)
+		UnregisterSnapshot(sysscan->snapshot);
+	pfree(sysscan);
+}
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c
new file mode 100644
index 0000000..5e22479
--- /dev/null
+++ b/src/backend/access/index/indexam.c
@@ -0,0 +1,984 @@
+/*-------------------------------------------------------------------------
+ *
+ * indexam.c
+ *	  general index access method routines
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/index/indexam.c
+ *
+ * INTERFACE ROUTINES
+ *		index_open		- open an index relation by relation OID
+ *		index_close		- close an index relation
+ *		index_beginscan - start a scan of an index with amgettuple
+ *		index_beginscan_bitmap - start a scan of an index with amgetbitmap
+ *		index_rescan	- restart a scan of an index
+ *		index_endscan	- end a scan
+ *		index_insert	- insert an index tuple into a relation
+ *		index_markpos	- mark a scan position
+ *		index_restrpos	- restore a scan position
+ *		index_parallelscan_estimate - estimate shared memory for parallel scan
+ *		index_parallelscan_initialize - initialize parallel scan
+ *		index_parallelrescan  - (re)start a parallel scan of an index
+ *		index_beginscan_parallel - join parallel index scan
+ *		index_getnext_tid	- get the next TID from a scan
+ *		index_fetch_heap		- get the scan's next heap tuple
+ *		index_getnext_slot	- get the next tuple from a scan
+ *		index_getbitmap - get all tuples from a scan
+ *		index_bulk_delete	- bulk deletion of index tuples
+ *		index_vacuum_cleanup	- post-deletion cleanup of an index
+ *		index_can_return	- does index support index-only scans?
+ *		index_getprocid - get a support procedure OID
+ *		index_getprocinfo - get a support procedure's lookup info
+ *
+ * NOTES
+ *		This file contains the index_ routines which used
+ *		to be a scattered collection of stuff in access/genam.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/amapi.h"
+#include "access/heapam.h"
+#include "access/reloptions.h"
+#include "access/relscan.h"
+#include "access/tableam.h"
+#include "access/transam.h"
+#include "access/xlog.h"
+#include "catalog/index.h"
+#include "catalog/pg_amproc.h"
+#include "catalog/pg_type.h"
+#include "commands/defrem.h"
+#include "nodes/makefuncs.h"
+#include "pgstat.h"
+#include "storage/bufmgr.h"
+#include "storage/lmgr.h"
+#include "storage/predicate.h"
+#include "utils/ruleutils.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+
+
+/* ----------------------------------------------------------------
+ *					macros used in index_ routines
+ *
+ * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
+ * to check that we don't try to scan or do retail insertions into an index
+ * that is currently being rebuilt or pending rebuild.  This helps to catch
+ * things that don't work when reindexing system catalogs.  The assertion
+ * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
+ * when calling the index AM's ambuild routine, and there is no reason for
+ * ambuild to call its subsidiary routines through this file.
+ * ----------------------------------------------------------------
+ */
+#define RELATION_CHECKS \
+( \
+	AssertMacro(RelationIsValid(indexRelation)), \
+	AssertMacro(PointerIsValid(indexRelation->rd_indam)), \
+	AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
+)
+
+#define SCAN_CHECKS \
+( \
+	AssertMacro(IndexScanIsValid(scan)), \
+	AssertMacro(RelationIsValid(scan->indexRelation)), \
+	AssertMacro(PointerIsValid(scan->indexRelation->rd_indam)) \
+)
+
+#define CHECK_REL_PROCEDURE(pname) \
+do { \
+	if (indexRelation->rd_indam->pname == NULL) \
+		elog(ERROR, "function \"%s\" is not defined for index \"%s\"", \
+			 CppAsString(pname), RelationGetRelationName(indexRelation)); \
+} while(0)
+
+#define CHECK_SCAN_PROCEDURE(pname) \
+do { \
+	if (scan->indexRelation->rd_indam->pname == NULL) \
+		elog(ERROR, "function \"%s\" is not defined for index \"%s\"", \
+			 CppAsString(pname), RelationGetRelationName(scan->indexRelation)); \
+} while(0)
+
+static IndexScanDesc index_beginscan_internal(Relation indexRelation,
+											  int nkeys, int norderbys, Snapshot snapshot,
+											  ParallelIndexScanDesc pscan, bool temp_snap);
+
+
+/* ----------------------------------------------------------------
+ *				   index_ interface functions
+ * ----------------------------------------------------------------
+ */
+
+/* ----------------
+ *		index_open - open an index relation by relation OID
+ *
+ *		If lockmode is not "NoLock", the specified kind of lock is
+ *		obtained on the index.  (Generally, NoLock should only be
+ *		used if the caller knows it has some appropriate lock on the
+ *		index already.)
+ *
+ *		An error is raised if the index does not exist.
+ *
+ *		This is a convenience routine adapted for indexscan use.
+ *		Some callers may prefer to use relation_open directly.
+ * ----------------
+ */
+Relation
+index_open(Oid relationId, LOCKMODE lockmode)
+{
+	Relation	r;
+
+	r = relation_open(relationId, lockmode);
+
+	if (r->rd_rel->relkind != RELKIND_INDEX &&
+		r->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not an index",
+						RelationGetRelationName(r))));
+
+	return r;
+}
+
+/* ----------------
+ *		index_close - close an index relation
+ *
+ *		If lockmode is not "NoLock", we then release the specified lock.
+ *
+ *		Note that it is often sensible to hold a lock beyond index_close;
+ *		in that case, the lock is released automatically at xact end.
+ * ----------------
+ */
+void
+index_close(Relation relation, LOCKMODE lockmode)
+{
+	LockRelId	relid = relation->rd_lockInfo.lockRelId;
+
+	Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
+
+	/* The relcache does the real work... */
+	RelationClose(relation);
+
+	if (lockmode != NoLock)
+		UnlockRelationId(&relid, lockmode);
+}
+
+/* ----------------
+ *		index_insert - insert an index tuple into a relation
+ * ----------------
+ */
+bool
+index_insert(Relation indexRelation,
+			 Datum *values,
+			 bool *isnull,
+			 ItemPointer heap_t_ctid,
+			 Relation heapRelation,
+			 IndexUniqueCheck checkUnique,
+			 bool indexUnchanged,
+			 IndexInfo *indexInfo)
+{
+	RELATION_CHECKS;
+	CHECK_REL_PROCEDURE(aminsert);
+
+	if (!(indexRelation->rd_indam->ampredlocks))
+		CheckForSerializableConflictIn(indexRelation,
+									   (ItemPointer) NULL,
+									   InvalidBlockNumber);
+
+	return indexRelation->rd_indam->aminsert(indexRelation, values, isnull,
+											 heap_t_ctid, heapRelation,
+											 checkUnique, indexUnchanged,
+											 indexInfo);
+}
+
+/*
+ * index_beginscan - start a scan of an index with amgettuple
+ *
+ * Caller must be holding suitable locks on the heap and the index.
+ */
+IndexScanDesc
+index_beginscan(Relation heapRelation,
+				Relation indexRelation,
+				Snapshot snapshot,
+				int nkeys, int norderbys)
+{
+	IndexScanDesc scan;
+
+	scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot, NULL, false);
+
+	/*
+	 * Save additional parameters into the scandesc.  Everything else was set
+	 * up by RelationGetIndexScan.
+	 */
+	scan->heapRelation = heapRelation;
+	scan->xs_snapshot = snapshot;
+
+	/* prepare to fetch index matches from table */
+	scan->xs_heapfetch = table_index_fetch_begin(heapRelation);
+
+	return scan;
+}
+
+/*
+ * index_beginscan_bitmap - start a scan of an index with amgetbitmap
+ *
+ * As above, caller had better be holding some lock on the parent heap
+ * relation, even though it's not explicitly mentioned here.
+ */
+IndexScanDesc
+index_beginscan_bitmap(Relation indexRelation,
+					   Snapshot snapshot,
+					   int nkeys)
+{
+	IndexScanDesc scan;
+
+	scan = index_beginscan_internal(indexRelation, nkeys, 0, snapshot, NULL, false);
+
+	/*
+	 * Save additional parameters into the scandesc.  Everything else was set
+	 * up by RelationGetIndexScan.
+	 */
+	scan->xs_snapshot = snapshot;
+
+	return scan;
+}
+
+/*
+ * index_beginscan_internal --- common code for index_beginscan variants
+ */
+static IndexScanDesc
+index_beginscan_internal(Relation indexRelation,
+						 int nkeys, int norderbys, Snapshot snapshot,
+						 ParallelIndexScanDesc pscan, bool temp_snap)
+{
+	IndexScanDesc scan;
+
+	RELATION_CHECKS;
+	CHECK_REL_PROCEDURE(ambeginscan);
+
+	if (!(indexRelation->rd_indam->ampredlocks))
+		PredicateLockRelation(indexRelation, snapshot);
+
+	/*
+	 * We hold a reference count to the relcache entry throughout the scan.
+	 */
+	RelationIncrementReferenceCount(indexRelation);
+
+	/*
+	 * Tell the AM to open a scan.
+	 */
+	scan = indexRelation->rd_indam->ambeginscan(indexRelation, nkeys,
+												norderbys);
+	/* Initialize information for parallel scan. */
+	scan->parallel_scan = pscan;
+	scan->xs_temp_snap = temp_snap;
+
+	return scan;
+}
+
+/* ----------------
+ *		index_rescan  - (re)start a scan of an index
+ *
+ * During a restart, the caller may specify a new set of scankeys and/or
+ * orderbykeys; but the number of keys cannot differ from what index_beginscan
+ * was told.  (Later we might relax that to "must not exceed", but currently
+ * the index AMs tend to assume that scan->numberOfKeys is what to believe.)
+ * To restart the scan without changing keys, pass NULL for the key arrays.
+ * (Of course, keys *must* be passed on the first call, unless
+ * scan->numberOfKeys is zero.)
+ * ----------------
+ */
+void
+index_rescan(IndexScanDesc scan,
+			 ScanKey keys, int nkeys,
+			 ScanKey orderbys, int norderbys)
+{
+	SCAN_CHECKS;
+	CHECK_SCAN_PROCEDURE(amrescan);
+
+	Assert(nkeys == scan->numberOfKeys);
+	Assert(norderbys == scan->numberOfOrderBys);
+
+	/* Release resources (like buffer pins) from table accesses */
+	if (scan->xs_heapfetch)
+		table_index_fetch_reset(scan->xs_heapfetch);
+
+	scan->kill_prior_tuple = false; /* for safety */
+	scan->xs_heap_continue = false;
+
+	scan->indexRelation->rd_indam->amrescan(scan, keys, nkeys,
+											orderbys, norderbys);
+}
+
+/* ----------------
+ *		index_endscan - end a scan
+ * ----------------
+ */
+void
+index_endscan(IndexScanDesc scan)
+{
+	SCAN_CHECKS;
+	CHECK_SCAN_PROCEDURE(amendscan);
+
+	/* Release resources (like buffer pins) from table accesses */
+	if (scan->xs_heapfetch)
+	{
+		table_index_fetch_end(scan->xs_heapfetch);
+		scan->xs_heapfetch = NULL;
+	}
+
+	/* End the AM's scan */
+	scan->indexRelation->rd_indam->amendscan(scan);
+
+	/* Release index refcount acquired by index_beginscan */
+	RelationDecrementReferenceCount(scan->indexRelation);
+
+	if (scan->xs_temp_snap)
+		UnregisterSnapshot(scan->xs_snapshot);
+
+	/* Release the scan data structure itself */
+	IndexScanEnd(scan);
+}
+
+/* ----------------
+ *		index_markpos  - mark a scan position
+ * ----------------
+ */
+void
+index_markpos(IndexScanDesc scan)
+{
+	SCAN_CHECKS;
+	CHECK_SCAN_PROCEDURE(ammarkpos);
+
+	scan->indexRelation->rd_indam->ammarkpos(scan);
+}
+
+/* ----------------
+ *		index_restrpos	- restore a scan position
+ *
+ * NOTE: this only restores the internal scan state of the index AM.  See
+ * comments for ExecRestrPos().
+ *
+ * NOTE: For heap, in the presence of HOT chains, mark/restore only works
+ * correctly if the scan's snapshot is MVCC-safe; that ensures that there's at
+ * most one returnable tuple in each HOT chain, and so restoring the prior
+ * state at the granularity of the index AM is sufficient.  Since the only
+ * current user of mark/restore functionality is nodeMergejoin.c, this
+ * effectively means that merge-join plans only work for MVCC snapshots.  This
+ * could be fixed if necessary, but for now it seems unimportant.
+ * ----------------
+ */
+void
+index_restrpos(IndexScanDesc scan)
+{
+	Assert(IsMVCCSnapshot(scan->xs_snapshot));
+
+	SCAN_CHECKS;
+	CHECK_SCAN_PROCEDURE(amrestrpos);
+
+	/* release resources (like buffer pins) from table accesses */
+	if (scan->xs_heapfetch)
+		table_index_fetch_reset(scan->xs_heapfetch);
+
+	scan->kill_prior_tuple = false; /* for safety */
+	scan->xs_heap_continue = false;
+
+	scan->indexRelation->rd_indam->amrestrpos(scan);
+}
+
+/*
+ * index_parallelscan_estimate - estimate shared memory for parallel scan
+ *
+ * Currently, we don't pass any information to the AM-specific estimator,
+ * so it can probably only return a constant.  In the future, we might need
+ * to pass more information.
+ */
+Size
+index_parallelscan_estimate(Relation indexRelation, Snapshot snapshot)
+{
+	Size		nbytes;
+
+	RELATION_CHECKS;
+
+	nbytes = offsetof(ParallelIndexScanDescData, ps_snapshot_data);
+	nbytes = add_size(nbytes, EstimateSnapshotSpace(snapshot));
+	nbytes = MAXALIGN(nbytes);
+
+	/*
+	 * If amestimateparallelscan is not provided, assume there is no
+	 * AM-specific data needed.  (It's hard to believe that could work, but
+	 * it's easy enough to cater to it here.)
+	 */
+	if (indexRelation->rd_indam->amestimateparallelscan != NULL)
+		nbytes = add_size(nbytes,
+						  indexRelation->rd_indam->amestimateparallelscan());
+
+	return nbytes;
+}
+
+/*
+ * index_parallelscan_initialize - initialize parallel scan
+ *
+ * We initialize both the ParallelIndexScanDesc proper and the AM-specific
+ * information which follows it.
+ *
+ * This function calls access method specific initialization routine to
+ * initialize am specific information.  Call this just once in the leader
+ * process; then, individual workers attach via index_beginscan_parallel.
+ */
+void
+index_parallelscan_initialize(Relation heapRelation, Relation indexRelation,
+							  Snapshot snapshot, ParallelIndexScanDesc target)
+{
+	Size		offset;
+
+	RELATION_CHECKS;
+
+	offset = add_size(offsetof(ParallelIndexScanDescData, ps_snapshot_data),
+					  EstimateSnapshotSpace(snapshot));
+	offset = MAXALIGN(offset);
+
+	target->ps_relid = RelationGetRelid(heapRelation);
+	target->ps_indexid = RelationGetRelid(indexRelation);
+	target->ps_offset = offset;
+	SerializeSnapshot(snapshot, target->ps_snapshot_data);
+
+	/* aminitparallelscan is optional; assume no-op if not provided by AM */
+	if (indexRelation->rd_indam->aminitparallelscan != NULL)
+	{
+		void	   *amtarget;
+
+		amtarget = OffsetToPointer(target, offset);
+		indexRelation->rd_indam->aminitparallelscan(amtarget);
+	}
+}
+
+/* ----------------
+ *		index_parallelrescan  - (re)start a parallel scan of an index
+ * ----------------
+ */
+void
+index_parallelrescan(IndexScanDesc scan)
+{
+	SCAN_CHECKS;
+
+	if (scan->xs_heapfetch)
+		table_index_fetch_reset(scan->xs_heapfetch);
+
+	/* amparallelrescan is optional; assume no-op if not provided by AM */
+	if (scan->indexRelation->rd_indam->amparallelrescan != NULL)
+		scan->indexRelation->rd_indam->amparallelrescan(scan);
+}
+
+/*
+ * index_beginscan_parallel - join parallel index scan
+ *
+ * Caller must be holding suitable locks on the heap and the index.
+ */
+IndexScanDesc
+index_beginscan_parallel(Relation heaprel, Relation indexrel, int nkeys,
+						 int norderbys, ParallelIndexScanDesc pscan)
+{
+	Snapshot	snapshot;
+	IndexScanDesc scan;
+
+	Assert(RelationGetRelid(heaprel) == pscan->ps_relid);
+	snapshot = RestoreSnapshot(pscan->ps_snapshot_data);
+	RegisterSnapshot(snapshot);
+	scan = index_beginscan_internal(indexrel, nkeys, norderbys, snapshot,
+									pscan, true);
+
+	/*
+	 * Save additional parameters into the scandesc.  Everything else was set
+	 * up by index_beginscan_internal.
+	 */
+	scan->heapRelation = heaprel;
+	scan->xs_snapshot = snapshot;
+
+	/* prepare to fetch index matches from table */
+	scan->xs_heapfetch = table_index_fetch_begin(heaprel);
+
+	return scan;
+}
+
+/* ----------------
+ * index_getnext_tid - get the next TID from a scan
+ *
+ * The result is the next TID satisfying the scan keys,
+ * or NULL if no more matching tuples exist.
+ * ----------------
+ */
+ItemPointer
+index_getnext_tid(IndexScanDesc scan, ScanDirection direction)
+{
+	bool		found;
+
+	SCAN_CHECKS;
+	CHECK_SCAN_PROCEDURE(amgettuple);
+
+	/* XXX: we should assert that a snapshot is pushed or registered */
+	Assert(TransactionIdIsValid(RecentXmin));
+
+	/*
+	 * The AM's amgettuple proc finds the next index entry matching the scan
+	 * keys, and puts the TID into scan->xs_heaptid.  It should also set
+	 * scan->xs_recheck and possibly scan->xs_itup/scan->xs_hitup, though we
+	 * pay no attention to those fields here.
+	 */
+	found = scan->indexRelation->rd_indam->amgettuple(scan, direction);
+
+	/* Reset kill flag immediately for safety */
+	scan->kill_prior_tuple = false;
+	scan->xs_heap_continue = false;
+
+	/* If we're out of index entries, we're done */
+	if (!found)
+	{
+		/* release resources (like buffer pins) from table accesses */
+		if (scan->xs_heapfetch)
+			table_index_fetch_reset(scan->xs_heapfetch);
+
+		return NULL;
+	}
+	Assert(ItemPointerIsValid(&scan->xs_heaptid));
+
+	pgstat_count_index_tuples(scan->indexRelation, 1);
+
+	/* Return the TID of the tuple we found. */
+	return &scan->xs_heaptid;
+}
+
+/* ----------------
+ *		index_fetch_heap - get the scan's next heap tuple
+ *
+ * The result is a visible heap tuple associated with the index TID most
+ * recently fetched by index_getnext_tid, or NULL if no more matching tuples
+ * exist.  (There can be more than one matching tuple because of HOT chains,
+ * although when using an MVCC snapshot it should be impossible for more than
+ * one such tuple to exist.)
+ *
+ * On success, the buffer containing the heap tup is pinned (the pin will be
+ * dropped in a future index_getnext_tid, index_fetch_heap or index_endscan
+ * call).
+ *
+ * Note: caller must check scan->xs_recheck, and perform rechecking of the
+ * scan keys if required.  We do not do that here because we don't have
+ * enough information to do it efficiently in the general case.
+ * ----------------
+ */
+bool
+index_fetch_heap(IndexScanDesc scan, TupleTableSlot *slot)
+{
+	bool		all_dead = false;
+	bool		found;
+
+	found = table_index_fetch_tuple(scan->xs_heapfetch, &scan->xs_heaptid,
+									scan->xs_snapshot, slot,
+									&scan->xs_heap_continue, &all_dead);
+
+	if (found)
+		pgstat_count_heap_fetch(scan->indexRelation);
+
+	/*
+	 * If we scanned a whole HOT chain and found only dead tuples, tell index
+	 * AM to kill its entry for that TID (this will take effect in the next
+	 * amgettuple call, in index_getnext_tid).  We do not do this when in
+	 * recovery because it may violate MVCC to do so.  See comments in
+	 * RelationGetIndexScan().
+	 */
+	if (!scan->xactStartedInRecovery)
+		scan->kill_prior_tuple = all_dead;
+
+	return found;
+}
+
+/* ----------------
+ *		index_getnext_slot - get the next tuple from a scan
+ *
+ * The result is true if a tuple satisfying the scan keys and the snapshot was
+ * found, false otherwise.  The tuple is stored in the specified slot.
+ *
+ * On success, resources (like buffer pins) are likely to be held, and will be
+ * dropped by a future index_getnext_tid, index_fetch_heap or index_endscan
+ * call).
+ *
+ * Note: caller must check scan->xs_recheck, and perform rechecking of the
+ * scan keys if required.  We do not do that here because we don't have
+ * enough information to do it efficiently in the general case.
+ * ----------------
+ */
+bool
+index_getnext_slot(IndexScanDesc scan, ScanDirection direction, TupleTableSlot *slot)
+{
+	for (;;)
+	{
+		if (!scan->xs_heap_continue)
+		{
+			ItemPointer tid;
+
+			/* Time to fetch the next TID from the index */
+			tid = index_getnext_tid(scan, direction);
+
+			/* If we're out of index entries, we're done */
+			if (tid == NULL)
+				break;
+
+			Assert(ItemPointerEquals(tid, &scan->xs_heaptid));
+		}
+
+		/*
+		 * Fetch the next (or only) visible heap tuple for this index entry.
+		 * If we don't find anything, loop around and grab the next TID from
+		 * the index.
+		 */
+		Assert(ItemPointerIsValid(&scan->xs_heaptid));
+		if (index_fetch_heap(scan, slot))
+			return true;
+	}
+
+	return false;
+}
+
+/* ----------------
+ *		index_getbitmap - get all tuples at once from an index scan
+ *
+ * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
+ * Since there's no interlock between the index scan and the eventual heap
+ * access, this is only safe to use with MVCC-based snapshots: the heap
+ * item slot could have been replaced by a newer tuple by the time we get
+ * to it.
+ *
+ * Returns the number of matching tuples found.  (Note: this might be only
+ * approximate, so it should only be used for statistical purposes.)
+ * ----------------
+ */
+int64
+index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
+{
+	int64		ntids;
+
+	SCAN_CHECKS;
+	CHECK_SCAN_PROCEDURE(amgetbitmap);
+
+	/* just make sure this is false... */
+	scan->kill_prior_tuple = false;
+
+	/*
+	 * have the am's getbitmap proc do all the work.
+	 */
+	ntids = scan->indexRelation->rd_indam->amgetbitmap(scan, bitmap);
+
+	pgstat_count_index_tuples(scan->indexRelation, ntids);
+
+	return ntids;
+}
+
+/* ----------------
+ *		index_bulk_delete - do mass deletion of index entries
+ *
+ *		callback routine tells whether a given main-heap tuple is
+ *		to be deleted
+ *
+ *		return value is an optional palloc'd struct of statistics
+ * ----------------
+ */
+IndexBulkDeleteResult *
+index_bulk_delete(IndexVacuumInfo *info,
+				  IndexBulkDeleteResult *istat,
+				  IndexBulkDeleteCallback callback,
+				  void *callback_state)
+{
+	Relation	indexRelation = info->index;
+
+	RELATION_CHECKS;
+	CHECK_REL_PROCEDURE(ambulkdelete);
+
+	return indexRelation->rd_indam->ambulkdelete(info, istat,
+												 callback, callback_state);
+}
+
+/* ----------------
+ *		index_vacuum_cleanup - do post-deletion cleanup of an index
+ *
+ *		return value is an optional palloc'd struct of statistics
+ * ----------------
+ */
+IndexBulkDeleteResult *
+index_vacuum_cleanup(IndexVacuumInfo *info,
+					 IndexBulkDeleteResult *istat)
+{
+	Relation	indexRelation = info->index;
+
+	RELATION_CHECKS;
+	CHECK_REL_PROCEDURE(amvacuumcleanup);
+
+	return indexRelation->rd_indam->amvacuumcleanup(info, istat);
+}
+
+/* ----------------
+ *		index_can_return
+ *
+ *		Does the index access method support index-only scans for the given
+ *		column?
+ * ----------------
+ */
+bool
+index_can_return(Relation indexRelation, int attno)
+{
+	RELATION_CHECKS;
+
+	/* amcanreturn is optional; assume false if not provided by AM */
+	if (indexRelation->rd_indam->amcanreturn == NULL)
+		return false;
+
+	return indexRelation->rd_indam->amcanreturn(indexRelation, attno);
+}
+
+/* ----------------
+ *		index_getprocid
+ *
+ *		Index access methods typically require support routines that are
+ *		not directly the implementation of any WHERE-clause query operator
+ *		and so cannot be kept in pg_amop.  Instead, such routines are kept
+ *		in pg_amproc.  These registered procedure OIDs are assigned numbers
+ *		according to a convention established by the access method.
+ *		The general index code doesn't know anything about the routines
+ *		involved; it just builds an ordered list of them for
+ *		each attribute on which an index is defined.
+ *
+ *		As of Postgres 8.3, support routines within an operator family
+ *		are further subdivided by the "left type" and "right type" of the
+ *		query operator(s) that they support.  The "default" functions for a
+ *		particular indexed attribute are those with both types equal to
+ *		the index opclass' opcintype (note that this is subtly different
+ *		from the indexed attribute's own type: it may be a binary-compatible
+ *		type instead).  Only the default functions are stored in relcache
+ *		entries --- access methods can use the syscache to look up non-default
+ *		functions.
+ *
+ *		This routine returns the requested default procedure OID for a
+ *		particular indexed attribute.
+ * ----------------
+ */
+RegProcedure
+index_getprocid(Relation irel,
+				AttrNumber attnum,
+				uint16 procnum)
+{
+	RegProcedure *loc;
+	int			nproc;
+	int			procindex;
+
+	nproc = irel->rd_indam->amsupport;
+
+	Assert(procnum > 0 && procnum <= (uint16) nproc);
+
+	procindex = (nproc * (attnum - 1)) + (procnum - 1);
+
+	loc = irel->rd_support;
+
+	Assert(loc != NULL);
+
+	return loc[procindex];
+}
+
+/* ----------------
+ *		index_getprocinfo
+ *
+ *		This routine allows index AMs to keep fmgr lookup info for
+ *		support procs in the relcache.  As above, only the "default"
+ *		functions for any particular indexed attribute are cached.
+ *
+ * Note: the return value points into cached data that will be lost during
+ * any relcache rebuild!  Therefore, either use the callinfo right away,
+ * or save it only after having acquired some type of lock on the index rel.
+ * ----------------
+ */
+FmgrInfo *
+index_getprocinfo(Relation irel,
+				  AttrNumber attnum,
+				  uint16 procnum)
+{
+	FmgrInfo   *locinfo;
+	int			nproc;
+	int			optsproc;
+	int			procindex;
+
+	nproc = irel->rd_indam->amsupport;
+	optsproc = irel->rd_indam->amoptsprocnum;
+
+	Assert(procnum > 0 && procnum <= (uint16) nproc);
+
+	procindex = (nproc * (attnum - 1)) + (procnum - 1);
+
+	locinfo = irel->rd_supportinfo;
+
+	Assert(locinfo != NULL);
+
+	locinfo += procindex;
+
+	/* Initialize the lookup info if first time through */
+	if (locinfo->fn_oid == InvalidOid)
+	{
+		RegProcedure *loc = irel->rd_support;
+		RegProcedure procId;
+
+		Assert(loc != NULL);
+
+		procId = loc[procindex];
+
+		/*
+		 * Complain if function was not found during IndexSupportInitialize.
+		 * This should not happen unless the system tables contain bogus
+		 * entries for the index opclass.  (If an AM wants to allow a support
+		 * function to be optional, it can use index_getprocid.)
+		 */
+		if (!RegProcedureIsValid(procId))
+			elog(ERROR, "missing support function %d for attribute %d of index \"%s\"",
+				 procnum, attnum, RelationGetRelationName(irel));
+
+		fmgr_info_cxt(procId, locinfo, irel->rd_indexcxt);
+
+		if (procnum != optsproc)
+		{
+			/* Initialize locinfo->fn_expr with opclass options Const */
+			bytea	  **attoptions = RelationGetIndexAttOptions(irel, false);
+			MemoryContext oldcxt = MemoryContextSwitchTo(irel->rd_indexcxt);
+
+			set_fn_opclass_options(locinfo, attoptions[attnum - 1]);
+
+			MemoryContextSwitchTo(oldcxt);
+		}
+	}
+
+	return locinfo;
+}
+
+/* ----------------
+ *		index_store_float8_orderby_distances
+ *
+ *		Convert AM distance function's results (that can be inexact)
+ *		to ORDER BY types and save them into xs_orderbyvals/xs_orderbynulls
+ *		for a possible recheck.
+ * ----------------
+ */
+void
+index_store_float8_orderby_distances(IndexScanDesc scan, Oid *orderByTypes,
+									 IndexOrderByDistance *distances,
+									 bool recheckOrderBy)
+{
+	int			i;
+
+	Assert(distances || !recheckOrderBy);
+
+	scan->xs_recheckorderby = recheckOrderBy;
+
+	for (i = 0; i < scan->numberOfOrderBys; i++)
+	{
+		if (orderByTypes[i] == FLOAT8OID)
+		{
+#ifndef USE_FLOAT8_BYVAL
+			/* must free any old value to avoid memory leakage */
+			if (!scan->xs_orderbynulls[i])
+				pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
+#endif
+			if (distances && !distances[i].isnull)
+			{
+				scan->xs_orderbyvals[i] = Float8GetDatum(distances[i].value);
+				scan->xs_orderbynulls[i] = false;
+			}
+			else
+			{
+				scan->xs_orderbyvals[i] = (Datum) 0;
+				scan->xs_orderbynulls[i] = true;
+			}
+		}
+		else if (orderByTypes[i] == FLOAT4OID)
+		{
+			/* convert distance function's result to ORDER BY type */
+			if (distances && !distances[i].isnull)
+			{
+				scan->xs_orderbyvals[i] = Float4GetDatum((float4) distances[i].value);
+				scan->xs_orderbynulls[i] = false;
+			}
+			else
+			{
+				scan->xs_orderbyvals[i] = (Datum) 0;
+				scan->xs_orderbynulls[i] = true;
+			}
+		}
+		else
+		{
+			/*
+			 * If the ordering operator's return value is anything else, we
+			 * don't know how to convert the float8 bound calculated by the
+			 * distance function to that.  The executor won't actually need
+			 * the order by values we return here, if there are no lossy
+			 * results, so only insist on converting if the *recheck flag is
+			 * set.
+			 */
+			if (scan->xs_recheckorderby)
+				elog(ERROR, "ORDER BY operator must return float8 or float4 if the distance function is lossy");
+			scan->xs_orderbynulls[i] = true;
+		}
+	}
+}
+
+/* ----------------
+ *      index_opclass_options
+ *
+ *      Parse opclass-specific options for index column.
+ * ----------------
+ */
+bytea *
+index_opclass_options(Relation indrel, AttrNumber attnum, Datum attoptions,
+					  bool validate)
+{
+	int			amoptsprocnum = indrel->rd_indam->amoptsprocnum;
+	Oid			procid = InvalidOid;
+	FmgrInfo   *procinfo;
+	local_relopts relopts;
+
+	/* fetch options support procedure if specified */
+	if (amoptsprocnum != 0)
+		procid = index_getprocid(indrel, attnum, amoptsprocnum);
+
+	if (!OidIsValid(procid))
+	{
+		Oid			opclass;
+		Datum		indclassDatum;
+		oidvector  *indclass;
+		bool		isnull;
+
+		if (!DatumGetPointer(attoptions))
+			return NULL;		/* ok, no options, no procedure */
+
+		/*
+		 * Report an error if the opclass's options-parsing procedure does not
+		 * exist but the opclass options are specified.
+		 */
+		indclassDatum = SysCacheGetAttr(INDEXRELID, indrel->rd_indextuple,
+										Anum_pg_index_indclass, &isnull);
+		Assert(!isnull);
+		indclass = (oidvector *) DatumGetPointer(indclassDatum);
+		opclass = indclass->values[attnum - 1];
+
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("operator class %s has no options",
+						generate_opclass_name(opclass))));
+	}
+
+	init_local_reloptions(&relopts, 0);
+
+	procinfo = index_getprocinfo(indrel, attnum, amoptsprocnum);
+
+	(void) FunctionCall1(procinfo, PointerGetDatum(&relopts));
+
+	return build_local_reloptions(&relopts, attoptions, validate);
+}