diff options
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 12081c2cda5..af668195618 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.123 2004/12/31 22:00:00 pgsql Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.123.4.1 2006/02/13 16:22:38 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -683,11 +683,14 @@ compare_tlist_datatypes(List *tlist, List *colTypes, * it will work correctly: sublinks will already have been transformed into * subplans in the qual, but not in the subquery). * - * 2. The qual must not refer to any subquery output columns that were + * 2. The qual must not refer to the whole-row output of the subquery + * (since there is no easy way to name that within the subquery itself). + * + * 3. The qual must not refer to any subquery output columns that were * found to have inconsistent types across a set operation tree by * subquery_is_pushdown_safe(). * - * 3. If the subquery uses DISTINCT ON, we must not push down any quals that + * 4. If the subquery uses DISTINCT ON, we must not push down any quals that * refer to non-DISTINCT output columns, because that could change the set * of rows returned. This condition is vacuous for DISTINCT, because then * there are no non-DISTINCT output columns, but unfortunately it's fairly @@ -695,7 +698,7 @@ compare_tlist_datatypes(List *tlist, List *colTypes, * parsetree representation. It's cheaper to just make sure all the Vars * in the qual refer to DISTINCT columns. * - * 4. We must not push down any quals that refer to subselect outputs that + * 5. We must not push down any quals that refer to subselect outputs that * return sets, else we'd introduce functions-returning-sets into the * subquery's WHERE/HAVING quals. */ @@ -724,6 +727,13 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual, Assert(var->varno == rti); + /* Check point 2 */ + if (var->varattno == 0) + { + safe = false; + break; + } + /* * We use a bitmapset to avoid testing the same attno more than * once. (NB: this only works because subquery outputs can't have @@ -733,7 +743,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual, continue; tested = bms_add_member(tested, var->varattno); - /* Check point 2 */ + /* Check point 3 */ if (differentTypes[var->varattno]) { safe = false; @@ -745,7 +755,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual, Assert(tle != NULL); Assert(!tle->resdom->resjunk); - /* If subquery uses DISTINCT or DISTINCT ON, check point 3 */ + /* If subquery uses DISTINCT or DISTINCT ON, check point 4 */ if (subquery->distinctClause != NIL && !targetIsInSortList(tle, subquery->distinctClause)) { @@ -754,7 +764,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual, break; } - /* Refuse functions returning sets (point 4) */ + /* Refuse functions returning sets (point 5) */ if (expression_returns_set((Node *) tle->expr)) { safe = false; |