Avoid pulling up sublinks from a subselect's targetlist. Works around

problems that occur if sublink is referenced via a join alias variable.
Perhaps this can be improved later, but a simple and safe fix is needed
for 7.3.1.

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 0e5afcc..ebb9f3d 100644 (file)
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.132 2002/11/29 21:39:11 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.133 2002/12/05 21:46:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -357,10 +357,14 @@ pull_up_subqueries(Query *parse, Node *jtnode, bool below_outer_join)
                         * nothing will happen after the first time.  We do have to be
                         * careful to copy everything we pull up, however, or risk
                         * having chunks of structure multiply linked.
+                        *
+                        * Note: 'false' is correct here even if we are within an outer
+                        * join in the upper query; the lower query starts with a clean
+                        * slate for outer-join semantics.
                         */
                        subquery->jointree = (FromExpr *)
                                pull_up_subqueries(subquery, (Node *) subquery->jointree,
-                                                                  below_outer_join);
+                                                                  false);
 
                        /*
                         * Now make a modifiable copy of the subquery that we can run
@@ -543,6 +547,20 @@ is_simple_subquery(Query *subquery)
                return false;
 
        /*
+        * Don't pull up a subquery that has any sublinks in its targetlist,
+        * either.  As of PG 7.3 this creates problems because the pulled-up
+        * expressions may go into join alias lists, and the sublinks would
+        * not get fixed because we do flatten_join_alias_vars() too late.
+        * Eventually we should do a complete flatten_join_alias_vars as the
+        * first step of preprocess_expression, and then we could probably
+        * support this.  (BUT: it might be a bad idea anyway, due to possibly
+        * causing multiple evaluations of an expensive sublink.)
+        */
+       if (subquery->hasSubLinks &&
+               contain_subplans((Node *) subquery->targetList))
+               return false;
+
+       /*
         * Hack: don't try to pull up a subquery with an empty jointree.
         * query_planner() will correctly generate a Result plan for a
         * jointree that's totally empty, but I don't think the right things