* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.39 2000/07/12 02:37:09 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.40 2000/08/06 04:13:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
PlannerQueryLevel++; /* we become child */
- /* Check to see if this node was already processed; if so we have
- * trouble. Someday should change tree representation so that we can
- * cope with multiple links to the same subquery, but for now...
+ /*
+ * Check to see if this node was already processed; if so we have
+ * trouble. We check to see if the linked-to Query appears to have
+ * been planned already, too.
*/
if (subquery == NULL)
+ elog(ERROR, "make_subplan: invalid expression structure (SubLink already processed?)");
+ if (subquery->base_rel_list != NIL)
elog(ERROR, "make_subplan: invalid expression structure (subquery already processed?)");
+ /*
+ * Copy the source Query node. This is a quick and dirty kluge to resolve
+ * the fact that the parser can generate trees with multiple links to the
+ * same sub-Query node, but the planner wants to scribble on the Query.
+ * Try to clean this up when we do querytree redesign...
+ */
+ subquery = (Query *) copyObject(subquery);
+
/*
* For an EXISTS subplan, tell lower-level planner to expect that only
* the first tuple will be retrieved. For ALL and ANY subplans, we