Fix logic error in add_paths_to_partial_grouping_rel.

robertmhaas · robertmhaas · commit 3bfe957761ac · 2018-02-27T13:23:50.000-05:00
Commit 3bf05e0 sometimes uses the cheapest_partial_path variable in this function to mean the cheapest one from the input rel and at other times the cheapest one from the partially grouped rel, but it never resets it, so we can end up with bad plans, leading to "ERROR: Aggref found in non-Agg plan node". Jeevan Chalke, per a report from Andreas Joseph Krogh and a separate off-list report from Rajkumar Raghuwanshi Discussion: http://postgr.es/m/CAM2+6=X9kxQoL2ZqZ00E6asBt9z+rfyWbOmhXJ0+8fPAyMZ9Jg@mail.gmail.com
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
@@ -6339,6 +6339,9 @@ add_paths_to_partial_grouping_rel(PlannerInfo *root,
 	 */
 	generate_gather_paths(root, partially_grouped_rel, true);
 
+	/* Get cheapest partial path from partially_grouped_rel */
+	cheapest_partial_path = linitial(partially_grouped_rel->partial_pathlist);
+
 	/*
 	 * generate_gather_paths won't consider sorting the cheapest path to match
 	 * the group keys and then applying a Gather Merge node to the result;
