C comment: add optimizer function reference

Reported-by: James Coleman
Discussion: https://postgr.es/m/CAAaqYe9F6uoMhAr+8rMLwvGzaKaSknPA0Wi3Ehtv8pbSYmJq-Q@mail.gmail.com

Backpatch-through: master

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index f75e0f99cb9c382980b8728cbbe6278cc271b5e5..b11b9399891098f0fd82486d85f90347da2a9afd 100644 (file)
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -3473,7 +3473,8 @@ standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
            /*
             * Except for the topmost scan/join rel, consider gathering
             * partial paths.  We'll do the same for the topmost scan/join rel
-            * once we know the final targetlist (see grouping_planner).
+            * once we know the final targetlist (see grouping_planner's and
+            * its call to apply_scanjoin_target_to_paths).
             */
            if (!bms_equal(rel->relids, root->all_query_rels))
                generate_useful_gather_paths(root, rel, false);