diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index f3a0a44fd88..d11f44e64d5 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -62,6 +62,9 @@ int			force_parallel_mode = FORCE_PARALLEL_OFF;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control before grouping_planner plans upper rels */
+create_upper_paths_hook_type create_upper_paths_hook = NULL;
+
 
 /* Expression kind codes for preprocess_expression */
 #define EXPRKIND_QUAL			0
@@ -459,6 +462,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	root->append_rel_list = NIL;
 	root->rowMarks = NIL;
 	memset(root->upper_rels, 0, sizeof(root->upper_rels));
+	memset(root->upper_targets, 0, sizeof(root->upper_targets));
 	root->processed_tlist = NIL;
 	root->grouping_map = NULL;
 	root->minmax_aggs = NIL;
@@ -1736,6 +1740,28 @@ grouping_planner(PlannerInfo *root, bool inheritance_update,
 			}
 		}
 
+		/*
+		 * Save the various upper-rel PathTargets we just computed into
+		 * root->upper_targets[].  The core code doesn't use this, but it
+		 * provides a convenient place for extensions to get at the info.  For
+		 * consistency, we save all the intermediate targets, even though some
+		 * of the corresponding upperrels might not be needed for this query.
+		 */
+		root->upper_targets[UPPERREL_FINAL] = final_target;
+		root->upper_targets[UPPERREL_WINDOW] = sort_input_target;
+		root->upper_targets[UPPERREL_GROUP_AGG] = grouping_target;
+
+		/*
+		 * Let extensions, particularly CustomScan providers, consider
+		 * injecting extension Paths into the query's upperrels, where they
+		 * will compete with the Paths we create below.  We pass the final
+		 * scan/join rel because that's not so easily findable from the
+		 * PlannerInfo struct; anything else the hook wants to know should be
+		 * obtainable via "root".
+		 */
+		if (create_upper_paths_hook)
+			(*create_upper_paths_hook) (root, current_rel);
+
 		/*
 		 * If we have grouping and/or aggregation, consider ways to implement
 		 * that.  We build a new upperrel representing the output of this
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index c8d5c66b396..75577bce2ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -909,6 +909,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->append_rel_list = NIL;
 	subroot->rowMarks = NIL;
 	memset(subroot->upper_rels, 0, sizeof(subroot->upper_rels));
+	memset(subroot->upper_targets, 0, sizeof(subroot->upper_targets));
 	subroot->processed_tlist = NIL;
 	subroot->grouping_map = NULL;
 	subroot->minmax_aggs = NIL;
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index b48a6183dc2..503269693ba 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -263,6 +263,9 @@ typedef struct PlannerInfo
 	/* Use fetch_upper_rel() to get any particular upper rel */
 	List	   *upper_rels[UPPERREL_FINAL + 1]; /* upper-rel RelOptInfos */
 
+	/* Result tlists chosen by grouping_planner for upper-stage processing */
+	struct PathTarget *upper_targets[UPPERREL_FINAL + 1];
+
 	/*
 	 * grouping_planner passes back its final processed targetlist here, for
 	 * use in relabeling the topmost tlist of the finished Plan.
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index 3fb7cb58cbd..a95e73fa93b 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -24,6 +24,11 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 												  ParamListInfo boundParams);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control before grouping_planner plans upper rels */
+typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
+												  RelOptInfo *scan_join_rel);
+extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;
+
 
 extern PlannedStmt *planner(Query *parse, int cursorOptions,
 		ParamListInfo boundParams);