1 files changed, 55 insertions, 10 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index efe073a3eeb..270c11901b7 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -81,8 +81,10 @@ static List *get_gating_quals(PlannerInfo *root, List *quals);
 static Plan *create_gating_plan(PlannerInfo *root, Path *path, Plan *plan,
 				   List *gating_quals);
 static Plan *create_join_plan(PlannerInfo *root, JoinPath *best_path);
-static Plan *create_append_plan(PlannerInfo *root, AppendPath *best_path);
-static Plan *create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path);
+static Plan *create_append_plan(PlannerInfo *root, AppendPath *best_path,
+				   int flags);
+static Plan *create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
+						 int flags);
 static Result *create_group_result_plan(PlannerInfo *root,
 						 GroupResultPath *best_path);
 static ProjectSet *create_project_set_plan(PlannerInfo *root, ProjectSetPath *best_path);
@@ -390,11 +392,13 @@ create_plan_recurse(PlannerInfo *root, Path *best_path, int flags)
 			break;
 		case T_Append:
 			plan = create_append_plan(root,
-									  (AppendPath *) best_path);
+									  (AppendPath *) best_path,
+									  flags);
 			break;
 		case T_MergeAppend:
 			plan = create_merge_append_plan(root,
-											(MergeAppendPath *) best_path);
+											(MergeAppendPath *) best_path,
+											flags);
 			break;
 		case T_Result:
 			if (IsA(best_path, ProjectionPath))
@@ -1054,10 +1058,12 @@ create_join_plan(PlannerInfo *root, JoinPath *best_path)
  *	  Returns a Plan node.
  */
 static Plan *
-create_append_plan(PlannerInfo *root, AppendPath *best_path)
+create_append_plan(PlannerInfo *root, AppendPath *best_path, int flags)
 {
 	Append	   *plan;
 	List	   *tlist = build_path_tlist(root, &best_path->path);
+	int			orig_tlist_length = list_length(tlist);
+	bool		tlist_was_changed = false;
 	List	   *pathkeys = best_path->path.pathkeys;
 	List	   *subplans = NIL;
 	ListCell   *subpaths;
@@ -1112,7 +1118,12 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
 
 	if (pathkeys != NIL)
 	{
-		/* Compute sort column info, and adjust the Append's tlist as needed */
+		/*
+		 * Compute sort column info, and adjust the Append's tlist as needed.
+		 * Because we pass adjust_tlist_in_place = true, we may ignore the
+		 * function result; it must be the same plan node.  However, we then
+		 * need to detect whether any tlist entries were added.
+		 */
 		(void) prepare_sort_from_pathkeys((Plan *) plan, pathkeys,
 										  best_path->path.parent->relids,
 										  NULL,
@@ -1122,6 +1133,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
 										  &nodeSortOperators,
 										  &nodeCollations,
 										  &nodeNullsFirst);
+		tlist_was_changed = (orig_tlist_length != list_length(plan->plan.targetlist));
 	}
 
 	/* Build the plan for each child */
@@ -1231,7 +1243,20 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
-	return (Plan *) plan;
+	/*
+	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
+	 * produce either the exact tlist or a narrow tlist, we should get rid of
+	 * the sort columns again.  We must inject a projection node to do so.
+	 */
+	if (tlist_was_changed && (flags & (CP_EXACT_TLIST | CP_SMALL_TLIST)))
+	{
+		tlist = list_truncate(list_copy(plan->plan.targetlist),
+							  orig_tlist_length);
+		return inject_projection_plan((Plan *) plan, tlist,
+									  plan->plan.parallel_safe);
+	}
+	else
+		return (Plan *) plan;
 }
 
 /*
@@ -1242,11 +1267,14 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
  *	  Returns a Plan node.
  */
 static Plan *
-create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
+create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path,
+						 int flags)
 {
 	MergeAppend *node = makeNode(MergeAppend);
 	Plan	   *plan = &node->plan;
 	List	   *tlist = build_path_tlist(root, &best_path->path);
+	int			orig_tlist_length = list_length(tlist);
+	bool		tlist_was_changed;
 	List	   *pathkeys = best_path->path.pathkeys;
 	List	   *subplans = NIL;
 	ListCell   *subpaths;
@@ -1265,7 +1293,12 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 	plan->lefttree = NULL;
 	plan->righttree = NULL;
 
-	/* Compute sort column info, and adjust MergeAppend's tlist as needed */
+	/*
+	 * Compute sort column info, and adjust MergeAppend's tlist as needed.
+	 * Because we pass adjust_tlist_in_place = true, we may ignore the
+	 * function result; it must be the same plan node.  However, we then need
+	 * to detect whether any tlist entries were added.
+	 */
 	(void) prepare_sort_from_pathkeys(plan, pathkeys,
 									  best_path->path.parent->relids,
 									  NULL,
@@ -1275,6 +1308,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 									  &node->sortOperators,
 									  &node->collations,
 									  &node->nullsFirst);
+	tlist_was_changed = (orig_tlist_length != list_length(plan->targetlist));
 
 	/*
 	 * Now prepare the child plans.  We must apply prepare_sort_from_pathkeys
@@ -1371,7 +1405,18 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path)
 	node->mergeplans = subplans;
 	node->part_prune_info = partpruneinfo;
 
-	return (Plan *) node;
+	/*
+	 * If prepare_sort_from_pathkeys added sort columns, but we were told to
+	 * produce either the exact tlist or a narrow tlist, we should get rid of
+	 * the sort columns again.  We must inject a projection node to do so.
+	 */
+	if (tlist_was_changed && (flags & (CP_EXACT_TLIST | CP_SMALL_TLIST)))
+	{
+		tlist = list_truncate(list_copy(plan->targetlist), orig_tlist_length);
+		return inject_projection_plan(plan, tlist, plan->parallel_safe);
+	}
+	else
+		return plan;
 }
 
 /*