Re: Problem about postponing gathering partial paths for topmost scan/join rel - Mailing list pgsql-hackers

To fix this problem, I'm thinking we can leverage 'root->all_baserels'
to tell if we are at the topmost scan/join rel, something like:

--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -3041,7 +3041,7 @@ standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels)
                         * partial paths.  We'll do the same for the topmost scan/join rel
                         * once we know the final targetlist (see grouping_planner).
                         */
-                       if (lev < levels_needed)
+                       if (!bms_equal(rel->relids, root->all_baserels))
                                generate_useful_gather_paths(root, rel, false);


Any thoughts?