1 files changed, 22 insertions, 13 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 28216629aa4..792ea84a818 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -250,7 +250,8 @@ static Plan *prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
 static EquivalenceMember *find_ec_member_for_tle(EquivalenceClass *ec,
 					   TargetEntry *tle,
 					   Relids relids);
-static Sort *make_sort_from_pathkeys(Plan *lefttree, List *pathkeys);
+static Sort *make_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
+						Relids relids);
 static Sort *make_sort_from_groupcols(List *groupcls,
 						 AttrNumber *grpColIdx,
 						 Plan *lefttree);
@@ -1652,7 +1653,7 @@ create_sort_plan(PlannerInfo *root, SortPath *best_path, int flags)
 	subplan = create_plan_recurse(root, best_path->subpath,
 								  flags | CP_SMALL_TLIST);
 
-	plan = make_sort_from_pathkeys(subplan, best_path->path.pathkeys);
+	plan = make_sort_from_pathkeys(subplan, best_path->path.pathkeys, NULL);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -3771,6 +3772,8 @@ create_mergejoin_plan(PlannerInfo *root,
 	ListCell   *lc;
 	ListCell   *lop;
 	ListCell   *lip;
+	Path	   *outer_path = best_path->jpath.outerjoinpath;
+	Path	   *inner_path = best_path->jpath.innerjoinpath;
 
 	/*
 	 * MergeJoin can project, so we don't have to demand exact tlists from the
@@ -3834,8 +3837,10 @@ create_mergejoin_plan(PlannerInfo *root,
 	 */
 	if (best_path->outersortkeys)
 	{
+		Relids		outer_relids = outer_path->parent->relids;
 		Sort	   *sort = make_sort_from_pathkeys(outer_plan,
-												   best_path->outersortkeys);
+												   best_path->outersortkeys,
+												   outer_relids);
 
 		label_sort_with_costsize(root, sort, -1.0);
 		outer_plan = (Plan *) sort;
@@ -3846,8 +3851,10 @@ create_mergejoin_plan(PlannerInfo *root,
 
 	if (best_path->innersortkeys)
 	{
+		Relids		inner_relids = inner_path->parent->relids;
 		Sort	   *sort = make_sort_from_pathkeys(inner_plan,
-												   best_path->innersortkeys);
+												   best_path->innersortkeys,
+												   inner_relids);
 
 		label_sort_with_costsize(root, sort, -1.0);
 		inner_plan = (Plan *) sort;
@@ -5525,8 +5532,9 @@ make_sort(Plan *lefttree, int numCols,
  * the output parameters *p_numsortkeys etc.
  *
  * When looking for matches to an EquivalenceClass's members, we will only
- * consider child EC members if they match 'relids'.  This protects against
- * possible incorrect matches to child expressions that contain no Vars.
+ * consider child EC members if they belong to given 'relids'.  This protects
+ * against possible incorrect matches to child expressions that contain no
+ * Vars.
  *
  * If reqColIdx isn't NULL then it contains sort key column numbers that
  * we should match.  This is used when making child plans for a MergeAppend;
@@ -5681,11 +5689,11 @@ prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
 					continue;
 
 				/*
-				 * Ignore child members unless they match the rel being
+				 * Ignore child members unless they belong to the rel being
 				 * sorted.
 				 */
 				if (em->em_is_child &&
-					!bms_equal(em->em_relids, relids))
+					!bms_is_subset(em->em_relids, relids))
 					continue;
 
 				sortexpr = em->em_expr;
@@ -5769,7 +5777,7 @@ prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
  * find_ec_member_for_tle
  *		Locate an EquivalenceClass member matching the given TLE, if any
  *
- * Child EC members are ignored unless they match 'relids'.
+ * Child EC members are ignored unless they belong to given 'relids'.
  */
 static EquivalenceMember *
 find_ec_member_for_tle(EquivalenceClass *ec,
@@ -5797,10 +5805,10 @@ find_ec_member_for_tle(EquivalenceClass *ec,
 			continue;
 
 		/*
-		 * Ignore child members unless they match the rel being sorted.
+		 * Ignore child members unless they belong to the rel being sorted.
 		 */
 		if (em->em_is_child &&
-			!bms_equal(em->em_relids, relids))
+			!bms_is_subset(em->em_relids, relids))
 			continue;
 
 		/* Match if same expression (after stripping relabel) */
@@ -5821,9 +5829,10 @@ find_ec_member_for_tle(EquivalenceClass *ec,
  *
  *	  'lefttree' is the node which yields input tuples
  *	  'pathkeys' is the list of pathkeys by which the result is to be sorted
+ *	  'relids' is the set of relations required by prepare_sort_from_pathkeys()
  */
 static Sort *
-make_sort_from_pathkeys(Plan *lefttree, List *pathkeys)
+make_sort_from_pathkeys(Plan *lefttree, List *pathkeys, Relids relids)
 {
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
@@ -5833,7 +5842,7 @@ make_sort_from_pathkeys(Plan *lefttree, List *pathkeys)
 
 	/* Compute sort column info, and adjust lefttree as needed */
 	lefttree = prepare_sort_from_pathkeys(lefttree, pathkeys,
-										  NULL,
+										  relids,
 										  NULL,
 										  false,
 										  &numsortkeys,