diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 16cc9269ef..9096017fea 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -1539,7 +1539,8 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
 												 child_sjinfo,
 												 child_sjinfo->jointype);
 			joinrel->part_rels[cnt_parts] = child_joinrel;
-			joinrel->live_parts = bms_add_member(joinrel->live_parts, cnt_parts);
+			if (!IS_DUMMY_REL(child_joinrel))
+				joinrel->live_parts = bms_add_member(joinrel->live_parts, cnt_parts);
 			joinrel->all_partrels = bms_add_members(joinrel->all_partrels,
 													child_joinrel->relids);
 		}