diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376..9bff793 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -109,7 +109,6 @@ blhandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = BLOOM_NSTRATEGIES;
 	amroutine->amsupport = BLOOM_NPROC;
 	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;
@@ -143,6 +142,7 @@ blhandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = NULL;
 	amroutine->aminitparallelscan = NULL;
 	amroutine->amparallelrescan = NULL;
+	amroutine->ammatchorderby = NULL;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 8f008dd..5cd06c7 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -88,7 +88,6 @@ brinhandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = 0;
 	amroutine->amsupport = BRIN_LAST_OPTIONAL_PROCNUM;
 	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;
@@ -122,6 +121,7 @@ brinhandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = NULL;
 	amroutine->aminitparallelscan = NULL;
 	amroutine->amparallelrescan = NULL;
+	amroutine->ammatchorderby = NULL;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/access/gin/ginutil.c b/src/backend/access/gin/ginutil.c
index afc2023..0f6714d 100644
--- a/src/backend/access/gin/ginutil.c
+++ b/src/backend/access/gin/ginutil.c
@@ -41,7 +41,6 @@ ginhandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = 0;
 	amroutine->amsupport = GINNProcs;
 	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;
@@ -75,6 +74,7 @@ ginhandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = NULL;
 	amroutine->aminitparallelscan = NULL;
 	amroutine->amparallelrescan = NULL;
+	amroutine->ammatchorderby = NULL;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c
index b75b3a8..77ca187 100644
--- a/src/backend/access/gist/gist.c
+++ b/src/backend/access/gist/gist.c
@@ -18,6 +18,7 @@
 #include "access/gistscan.h"
 #include "catalog/pg_collation.h"
 #include "miscadmin.h"
+#include "optimizer/paths.h"
 #include "storage/lmgr.h"
 #include "storage/predicate.h"
 #include "nodes/execnodes.h"
@@ -64,7 +65,6 @@ gisthandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = 0;
 	amroutine->amsupport = GISTNProcs;
 	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = true;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;
@@ -98,6 +98,7 @@ gisthandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = NULL;
 	amroutine->aminitparallelscan = NULL;
 	amroutine->amparallelrescan = NULL;
+	amroutine->ammatchorderby = match_orderbyop_pathkeys;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index f1f01a0..bb5c6a1 100644
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -59,7 +59,6 @@ hashhandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = HTMaxStrategyNumber;
 	amroutine->amsupport = HASHNProcs;
 	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = false;
 	amroutine->amcanbackward = true;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = false;
@@ -93,6 +92,7 @@ hashhandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = NULL;
 	amroutine->aminitparallelscan = NULL;
 	amroutine->amparallelrescan = NULL;
+	amroutine->ammatchorderby = NULL;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 98917de..c56ee5e 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -110,7 +110,6 @@ bthandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = BTMaxStrategyNumber;
 	amroutine->amsupport = BTNProcs;
 	amroutine->amcanorder = true;
-	amroutine->amcanorderbyop = false;
 	amroutine->amcanbackward = true;
 	amroutine->amcanunique = true;
 	amroutine->amcanmulticol = true;
@@ -144,6 +143,7 @@ bthandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = btestimateparallelscan;
 	amroutine->aminitparallelscan = btinitparallelscan;
 	amroutine->amparallelrescan = btparallelrescan;
+	amroutine->ammatchorderby = NULL;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/access/spgist/spgutils.c b/src/backend/access/spgist/spgutils.c
index 8e63c1f..37de33c 100644
--- a/src/backend/access/spgist/spgutils.c
+++ b/src/backend/access/spgist/spgutils.c
@@ -22,6 +22,7 @@
 #include "access/transam.h"
 #include "access/xact.h"
 #include "catalog/pg_amop.h"
+#include "optimizer/paths.h"
 #include "storage/bufmgr.h"
 #include "storage/indexfsm.h"
 #include "storage/lmgr.h"
@@ -31,7 +32,6 @@
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 
-
 /*
  * SP-GiST handler function: return IndexAmRoutine with access method parameters
  * and callbacks.
@@ -44,7 +44,6 @@ spghandler(PG_FUNCTION_ARGS)
 	amroutine->amstrategies = 0;
 	amroutine->amsupport = SPGISTNProc;
 	amroutine->amcanorder = false;
-	amroutine->amcanorderbyop = true;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = false;
@@ -78,6 +77,7 @@ spghandler(PG_FUNCTION_ARGS)
 	amroutine->amestimateparallelscan = NULL;
 	amroutine->aminitparallelscan = NULL;
 	amroutine->amparallelrescan = NULL;
+	amroutine->ammatchorderby = match_orderbyop_pathkeys;
 
 	PG_RETURN_POINTER(amroutine);
 }
diff --git a/src/backend/commands/opclasscmds.c b/src/backend/commands/opclasscmds.c
index 5d73848..a595c79 100644
--- a/src/backend/commands/opclasscmds.c
+++ b/src/backend/commands/opclasscmds.c
@@ -1097,7 +1097,7 @@ assignOperTypes(OpFamilyMember *member, Oid amoid, Oid typeoid)
 		 */
 		IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(amoid, false);
 
-		if (!amroutine->amcanorderbyop)
+		if (!amroutine->ammatchorderby)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 					 errmsg("access method \"%s\" does not support ordering operators",
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 324356e..805abd2 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -198,7 +198,7 @@ IndexNextWithReorder(IndexScanState *node)
 	 * with just Asserting here because the system will not try to run the
 	 * plan backwards if ExecSupportsBackwardScan() says it won't work.
 	 * Currently, that is guaranteed because no index AMs support both
-	 * amcanorderbyop and amcanbackward; if any ever do,
+	 * ammatchorderby and amcanbackward; if any ever do,
 	 * ExecSupportsBackwardScan() will need to consider indexorderbys
 	 * explicitly.
 	 */
@@ -1148,7 +1148,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
  * 5. NullTest ("indexkey IS NULL/IS NOT NULL").  We just fill in the
  * ScanKey properly.
  *
- * This code is also used to prepare ORDER BY expressions for amcanorderbyop
+ * This code is also used to prepare ORDER BY expressions for ammatchorderby
  * indexes.  The behavior is exactly the same, except that we have to look up
  * the operator differently.  Note that only cases 1 and 2 are currently
  * possible for ORDER BY.
diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index 3434219..6cf0b0d 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -17,6 +17,7 @@
 
 #include <math.h>
 
+#include "access/amapi.h"
 #include "access/stratnum.h"
 #include "access/sysattr.h"
 #include "catalog/pg_am.h"
@@ -182,8 +183,9 @@ static IndexClause *expand_indexqual_rowcompare(RestrictInfo *rinfo,
 							Oid expr_op,
 							bool var_on_left);
 static void match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
+						List *index_clauses,
 						List **orderby_clauses_p,
-						List **clause_columns_p);
+						List **orderby_clause_columns_p);
 static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
 							int indexcol, Expr *clause, Oid pk_opfamily);
 static bool ec_member_matches_indexcol(PlannerInfo *root, RelOptInfo *rel,
@@ -1001,10 +1003,11 @@ build_index_paths(PlannerInfo *root, RelOptInfo *rel,
 		orderbyclauses = NIL;
 		orderbyclausecols = NIL;
 	}
-	else if (index->amcanorderbyop && pathkeys_possibly_useful)
+	else if (index->ammatchorderby && pathkeys_possibly_useful)
 	{
 		/* see if we can generate ordering operators for query_pathkeys */
 		match_pathkeys_to_index(index, root->query_pathkeys,
+								index_clauses,
 								&orderbyclauses,
 								&orderbyclausecols);
 		if (orderbyclauses)
@@ -2927,6 +2930,113 @@ match_rowcompare_to_indexcol(RestrictInfo *rinfo,
 	return NULL;
 }
 
+/****************************************************************************
+ *				----  ROUTINES TO CHECK ORDERING OPERATORS	----
+ ****************************************************************************/
+
+/*
+ * Try to match order-by-operator pathkey to the specified index column
+ * (*indexcol_p >= 0) or to all index columns (*indexcol_p < 0).
+ *
+ * Returned matched index clause exression.
+ * Number of matched index column is returned in *indexcol_p.
+ */
+Expr *
+match_orderbyop_pathkey(IndexOptInfo *index, PathKey *pathkey, int *indexcol_p)
+{
+	ListCell   *lc;
+
+	/* Pathkey must request default sort order for the target opfamily */
+	if (pathkey->pk_strategy != BTLessStrategyNumber ||
+		pathkey->pk_nulls_first)
+		return NULL;
+
+	/* If eclass is volatile, no hope of using an indexscan */
+	if (pathkey->pk_eclass->ec_has_volatile)
+		return NULL;
+
+	/*
+	 * Try to match eclass member expression(s) to index.  Note that child EC
+	 * members are considered, but only when they belong to the target
+	 * relation.  (Unlike regular members, the same expression could be a
+	 * child member of more than one EC.  Therefore, the same index could be
+	 * considered to match more than one pathkey list, which is OK here.  See
+	 * also get_eclass_for_sort_expr.)
+	 */
+	foreach(lc, pathkey->pk_eclass->ec_members)
+	{
+		EquivalenceMember *member = lfirst_node(EquivalenceMember, lc);
+		Expr	   *expr;
+
+		/* No possibility of match if it references other relations. */
+		if (!bms_equal(member->em_relids, index->rel->relids))
+			continue;
+
+		/* If *indexcol_p is non-negative then try to match only to it. */
+		if (*indexcol_p >= 0)
+		{
+			expr = match_clause_to_ordering_op(index, *indexcol_p,
+											   member->em_expr,
+											   pathkey->pk_opfamily);
+
+			if (expr)
+				return expr;	/* don't want to look at remaining members */
+		}
+		else
+		{
+			int			indexcol;
+
+			/*
+			 * We allow any column of this index to match each pathkey; they
+			 * don't have to match left-to-right as you might expect.
+			 */
+			for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
+			{
+				expr = match_clause_to_ordering_op(index, indexcol,
+												   member->em_expr,
+												   pathkey->pk_opfamily);
+				if (expr)
+				{
+					*indexcol_p = indexcol;
+					return expr;	/* don't want to look at remaining members */
+				}
+			}
+		}
+	}
+
+	return NULL;
+}
+
+/* Try to match order-by-operator pathkeys to any index columns. */
+bool
+match_orderbyop_pathkeys(IndexOptInfo *index, List *pathkeys,
+						 List *index_clauses, List **orderby_clauses_p,
+						 List **orderby_clausecols_p)
+{
+	ListCell   *lc;
+
+	foreach(lc, pathkeys)
+	{
+		PathKey    *pathkey = lfirst_node(PathKey, lc);
+		Expr	   *expr;
+		int			indexcol = -1;	/* match all index columns */
+
+		expr = match_orderbyop_pathkey(index, pathkey, &indexcol);
+
+		/*
+		 * Note: for any failure to match, we just return NIL immediately.
+		 * There is no value in matching just some of the pathkeys.
+		 */
+		if (!expr)
+			return false;
+
+		*orderby_clauses_p = lappend(*orderby_clauses_p, expr);
+		*orderby_clausecols_p = lappend_int(*orderby_clausecols_p, indexcol);
+	}
+
+	return true;				/* success */
+}
+
 /*
  * expand_indexqual_rowcompare --- expand a single indexqual condition
  *		that is a RowCompareExpr
@@ -3183,92 +3293,31 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
  */
 static void
 match_pathkeys_to_index(IndexOptInfo *index, List *pathkeys,
+						List *index_clauses,
 						List **orderby_clauses_p,
-						List **clause_columns_p)
+						List **orderby_clause_columns_p)
 {
 	List	   *orderby_clauses = NIL;
-	List	   *clause_columns = NIL;
-	ListCell   *lc1;
-
-	*orderby_clauses_p = NIL;	/* set default results */
-	*clause_columns_p = NIL;
+	List	   *orderby_clause_columns = NIL;
+	ammatchorderby_function ammatchorderby =
+	(ammatchorderby_function) index->ammatchorderby;
 
-	/* Only indexes with the amcanorderbyop property are interesting here */
-	if (!index->amcanorderbyop)
-		return;
-
-	foreach(lc1, pathkeys)
+	/* Only indexes with the ammatchorderby function are interesting here */
+	if (ammatchorderby &&
+		ammatchorderby(index, pathkeys, index_clauses,
+					   &orderby_clauses, &orderby_clause_columns))
 	{
-		PathKey    *pathkey = (PathKey *) lfirst(lc1);
-		bool		found = false;
-		ListCell   *lc2;
-
-		/*
-		 * Note: for any failure to match, we just return NIL immediately.
-		 * There is no value in matching just some of the pathkeys.
-		 */
-
-		/* Pathkey must request default sort order for the target opfamily */
-		if (pathkey->pk_strategy != BTLessStrategyNumber ||
-			pathkey->pk_nulls_first)
-			return;
-
-		/* If eclass is volatile, no hope of using an indexscan */
-		if (pathkey->pk_eclass->ec_has_volatile)
-			return;
-
-		/*
-		 * Try to match eclass member expression(s) to index.  Note that child
-		 * EC members are considered, but only when they belong to the target
-		 * relation.  (Unlike regular members, the same expression could be a
-		 * child member of more than one EC.  Therefore, the same index could
-		 * be considered to match more than one pathkey list, which is OK
-		 * here.  See also get_eclass_for_sort_expr.)
-		 */
-		foreach(lc2, pathkey->pk_eclass->ec_members)
-		{
-			EquivalenceMember *member = (EquivalenceMember *) lfirst(lc2);
-			int			indexcol;
-
-			/* No possibility of match if it references other relations */
-			if (!bms_equal(member->em_relids, index->rel->relids))
-				continue;
+		Assert(list_length(pathkeys) == list_length(orderby_clauses));
+		Assert(list_length(pathkeys) == list_length(orderby_clause_columns));
 
-			/*
-			 * We allow any column of the index to match each pathkey; they
-			 * don't have to match left-to-right as you might expect.  This is
-			 * correct for GiST, and it doesn't matter for SP-GiST because
-			 * that doesn't handle multiple columns anyway, and no other
-			 * existing AMs support amcanorderbyop.  We might need different
-			 * logic in future for other implementations.
-			 */
-			for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++)
-			{
-				Expr	   *expr;
-
-				expr = match_clause_to_ordering_op(index,
-												   indexcol,
-												   member->em_expr,
-												   pathkey->pk_opfamily);
-				if (expr)
-				{
-					orderby_clauses = lappend(orderby_clauses, expr);
-					clause_columns = lappend_int(clause_columns, indexcol);
-					found = true;
-					break;
-				}
-			}
-
-			if (found)			/* don't want to look at remaining members */
-				break;
-		}
-
-		if (!found)				/* fail if no match for this pathkey */
-			return;
+		*orderby_clauses_p = orderby_clauses;	/* success! */
+		*orderby_clause_columns_p = orderby_clause_columns;
+	}
+	else
+	{
+		*orderby_clauses_p = NIL;	/* set default results */
+		*orderby_clause_columns_p = NIL;
 	}
-
-	*orderby_clauses_p = orderby_clauses;	/* success! */
-	*clause_columns_p = clause_columns;
 }
 
 /*
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index d6dc83c..2d81fd1 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -267,7 +267,7 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 
 			/* We copy just the fields we need, not all of rd_indam */
 			amroutine = indexRelation->rd_indam;
-			info->amcanorderbyop = amroutine->amcanorderbyop;
+			info->ammatchorderby = amroutine->ammatchorderby;
 			info->amoptionalkey = amroutine->amoptionalkey;
 			info->amsearcharray = amroutine->amsearcharray;
 			info->amsearchnulls = amroutine->amsearchnulls;
diff --git a/src/backend/utils/adt/amutils.c b/src/backend/utils/adt/amutils.c
index 060ffe5..3907065 100644
--- a/src/backend/utils/adt/amutils.c
+++ b/src/backend/utils/adt/amutils.c
@@ -298,7 +298,7 @@ indexam_property(FunctionCallInfo fcinfo,
 				 * a nonkey column, and null otherwise (meaning we don't
 				 * know).
 				 */
-				if (!iskey || !routine->amcanorderbyop)
+				if (!iskey || !routine->ammatchorderby)
 				{
 					res = false;
 					isnull = false;
diff --git a/src/include/access/amapi.h b/src/include/access/amapi.h
index 653ddc9..d8fb7d3 100644
--- a/src/include/access/amapi.h
+++ b/src/include/access/amapi.h
@@ -21,6 +21,9 @@
  */
 struct PlannerInfo;
 struct IndexPath;
+struct IndexOptInfo;
+struct PathKey;
+struct Expr;
 
 /* Likewise, this file shouldn't depend on execnodes.h. */
 struct IndexInfo;
@@ -140,6 +143,13 @@ typedef void (*ammarkpos_function) (IndexScanDesc scan);
 /* restore marked scan position */
 typedef void (*amrestrpos_function) (IndexScanDesc scan);
 
+/* does AM support ORDER BY result of an operator on indexed column? */
+typedef bool (*ammatchorderby_function) (struct IndexOptInfo *index,
+										 List *pathkeys,
+										 List *index_clauses,
+										 List **orderby_clauses_p,
+										 List **orderby_clause_columns_p);
+
 /*
  * Callback function signatures - for parallel index scans.
  */
@@ -170,8 +180,6 @@ typedef struct IndexAmRoutine
 	uint16		amsupport;
 	/* does AM support ORDER BY indexed column's value? */
 	bool		amcanorder;
-	/* does AM support ORDER BY result of an operator on indexed column? */
-	bool		amcanorderbyop;
 	/* does AM support backward scanning? */
 	bool		amcanbackward;
 	/* does AM support UNIQUE indexes? */
@@ -221,6 +229,7 @@ typedef struct IndexAmRoutine
 	amendscan_function amendscan;
 	ammarkpos_function ammarkpos;	/* can be NULL */
 	amrestrpos_function amrestrpos; /* can be NULL */
+	ammatchorderby_function ammatchorderby; /* can be NULL */
 
 	/* interface functions to support parallel index scans */
 	amestimateparallelscan_function amestimateparallelscan; /* can be NULL */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index a008ae0..4680cb8 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -814,7 +814,6 @@ struct IndexOptInfo
 	bool		hypothetical;	/* true if index doesn't really exist */
 
 	/* Remaining fields are copied from the index AM's API struct: */
-	bool		amcanorderbyop; /* does AM support order by operator result? */
 	bool		amoptionalkey;	/* can query omit key for the first column? */
 	bool		amsearcharray;	/* can AM handle ScalarArrayOpExpr quals? */
 	bool		amsearchnulls;	/* can AM search for NULL/NOT NULL entries? */
@@ -823,6 +822,12 @@ struct IndexOptInfo
 	bool		amcanparallel;	/* does AM support parallel scan? */
 	/* Rather than include amapi.h here, we declare amcostestimate like this */
 	void		(*amcostestimate) ();	/* AM's cost estimator */
+	/* AM order-by match function */
+	bool		(*ammatchorderby) (struct IndexOptInfo *index,
+								   List *pathkeys,
+								   List *index_clause_columns,
+								   List **orderby_clauses_p,
+								   List **orderby_clause_columns_p);
 };
 
 /*
@@ -1133,7 +1138,7 @@ typedef struct Path
  * An empty list implies a full index scan.
  *
  * 'indexorderbys', if not NIL, is a list of ORDER BY expressions that have
- * been found to be usable as ordering operators for an amcanorderbyop index.
+ * been found to be usable as ordering operators for an ammatchorderby index.
  * The list must match the path's pathkeys, ie, one expression per pathkey
  * in the same order.  These are not RestrictInfos, just bare expressions,
  * since they generally won't yield booleans.  It's guaranteed that each
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c2..bd6ce97 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -388,7 +388,7 @@ typedef struct SampleScan
  * indexorderbyops is a list of the OIDs of the operators used to sort the
  * ORDER BY expressions.  This is used together with indexorderbyorig to
  * recheck ordering at run time.  (Note that indexorderby, indexorderbyorig,
- * and indexorderbyops are used for amcanorderbyop cases, not amcanorder.)
+ * and indexorderbyops are used for ammatchorderby cases, not amcanorder.)
  *
  * indexorderdir specifies the scan ordering, for indexscans on amcanorder
  * indexes (for other indexes it should be "don't care").
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 040335a..e9f4f75 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -79,6 +79,11 @@ extern bool indexcol_is_bool_constant_for_query(IndexOptInfo *index,
 extern bool match_index_to_operand(Node *operand, int indexcol,
 					   IndexOptInfo *index);
 extern void check_index_predicates(PlannerInfo *root, RelOptInfo *rel);
+extern Expr *match_orderbyop_pathkey(IndexOptInfo *index, PathKey *pathkey,
+						int *indexcol_p);
+extern bool match_orderbyop_pathkeys(IndexOptInfo *index, List *pathkeys,
+						 List *index_clauses, List **orderby_clauses_p,
+						 List **orderby_clause_columns_p);
 
 /*
  * tidpath.h