Fix parallel hash join path search.

robertmhaas · robertmhaas · commit 655393a022bd · 2017-03-07T10:22:07.000-05:00
When the very cheapest path is not parallel-safe, we want to instead use the cheapest unparameterized path that is. The old code searched innerrel->cheapest_parameterized_paths, but that isn't right, because the path we want may not be in that list. Search innerrel->pathlist instead. Spotted by Dilip Kumar. Discussion: http://postgr.es/m/CAFiTN-szCEcZrQm0i_w4xqSaRUTOUFstNu32Zn4rxxDcoa8gnA@mail.gmail.com
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
@@ -1510,17 +1510,17 @@ hash_inner_and_outer(PlannerInfo *root,
 			/*
 			 * Normally, given that the joinrel is parallel-safe, the cheapest
 			 * total inner path will also be parallel-safe, but if not, we'll
-			 * have to search cheapest_parameterized_paths for the cheapest
-			 * safe, unparameterized inner path.  If doing JOIN_UNIQUE_INNER,
-			 * we can't use any alternative inner path.
+			 * have to search for the cheapest safe, unparameterized inner
+			 * path.  If doing JOIN_UNIQUE_INNER, we can't use any alternative
+			 * inner path.
 			 */
 			if (cheapest_total_inner->parallel_safe)
 				cheapest_safe_inner = cheapest_total_inner;
 			else if (save_jointype != JOIN_UNIQUE_INNER)
 			{
 				ListCell   *lc;
 
-				foreach(lc, innerrel->cheapest_parameterized_paths)
+				foreach(lc, innerrel->pathlist)
 				{
 					Path	   *innerpath = (Path *) lfirst(lc);
 
