Skip invoking set_uppernode_references() for a RESULT node

that has no subplan --- saves a material amount of time for a simple
INSERT ... VALUES query.

src/backend/optimizer/plan/setrefs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.57 1999/08/22 20:14:48 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.58 1999/10/30 23:07:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,8 +110,13 @@ set_plan_references(Plan *plan)
 			set_uppernode_references(plan, (Index) 0);
 			break;
 		case T_Result:
-			/* XXX why does Result use a different subvarno? */
-			set_uppernode_references(plan, (Index) OUTER);
+			/* Result may or may not have a subplan; no need to fix up
+			 * subplan references if it hasn't got one...
+			 *
+			 * XXX why does Result use a different subvarno from Agg/Group?
+			 */
+			if (plan->lefttree != NULL)
+				set_uppernode_references(plan, (Index) OUTER);
 			fix_opids(((Result *) plan)->resconstantqual);
 			break;
 		case T_Append: