88 *
99 *
1010 * IDENTIFICATION
11- * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.142 2006/02/04 23:03:20 tgl Exp $
11+ * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.143 2006/02/13 16:22:23 tgl Exp $
1212 *
1313 *-------------------------------------------------------------------------
1414 */
@@ -816,19 +816,22 @@ compare_tlist_datatypes(List *tlist, List *colTypes,
816816 * it will work correctly: sublinks will already have been transformed into
817817 * subplans in the qual, but not in the subquery).
818818 *
819- * 2. The qual must not refer to any subquery output columns that were
819+ * 2. The qual must not refer to the whole-row output of the subquery
820+ * (since there is no easy way to name that within the subquery itself).
821+ *
822+ * 3. The qual must not refer to any subquery output columns that were
820823 * found to have inconsistent types across a set operation tree by
821824 * subquery_is_pushdown_safe().
822825 *
823- *3 . If the subquery uses DISTINCT ON, we must not push down any quals that
826+ *4 . If the subquery uses DISTINCT ON, we must not push down any quals that
824827 * refer to non-DISTINCT output columns, because that could change the set
825828 * of rows returned. This condition is vacuous for DISTINCT, because then
826829 * there are no non-DISTINCT output columns, but unfortunately it's fairly
827830 * expensive to tell the difference between DISTINCT and DISTINCT ON in the
828831 * parsetree representation. It's cheaper to just make sure all the Vars
829832 * in the qual refer to DISTINCT columns.
830833 *
831- *4 . We must not push down any quals that refer to subselect outputs that
834+ *5 . We must not push down any quals that refer to subselect outputs that
832835 * return sets, else we'd introduce functions-returning-sets into the
833836 * subquery's WHERE/HAVING quals.
834837 */
@@ -857,6 +860,13 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
857860
858861Assert (var -> varno == rti );
859862
863+ /* Check point 2 */
864+ if (var -> varattno == 0 )
865+ {
866+ safe = false;
867+ break ;
868+ }
869+
860870/*
861871 * We use a bitmapset to avoid testing the same attno more than once.
862872 * (NB: this only works because subquery outputs can't have negative
@@ -866,7 +876,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
866876continue ;
867877tested = bms_add_member (tested ,var -> varattno );
868878
869- /* Check point2 */
879+ /* Check point3 */
870880if (differentTypes [var -> varattno ])
871881{
872882safe = false;
@@ -878,7 +888,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
878888Assert (tle != NULL );
879889Assert (!tle -> resjunk );
880890
881- /* If subquery uses DISTINCT or DISTINCT ON, check point3 */
891+ /* If subquery uses DISTINCT or DISTINCT ON, check point4 */
882892if (subquery -> distinctClause != NIL &&
883893!targetIsInSortList (tle ,subquery -> distinctClause ))
884894{
@@ -887,7 +897,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
887897break ;
888898}
889899
890- /* Refuse functions returning sets (point4 ) */
900+ /* Refuse functions returning sets (point5 ) */
891901if (expression_returns_set ((Node * )tle -> expr ))
892902{
893903safe = false;