diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index b0553894c24..17eebc67647 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 1.177 2008/11/15 19:43:46 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.178 2008/12/28 18:53:56 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -929,10 +929,13 @@ standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels) * 1. If the subquery has a LIMIT clause, we must not push down any quals, * since that could change the set of rows returned. * - * 2. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push + * 2. If the subquery contains any window functions, we can't push quals + * into it, because that would change the results. + * + * 3. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push * quals into it, because that would change the results. * - * 3. For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can + * 4. For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can * push quals into each component query, but the quals can only reference * subquery columns that suffer no type coercions in the set operation. * Otherwise there are possible semantic gotchas. So, we check the @@ -950,6 +953,10 @@ subquery_is_pushdown_safe(Query *subquery, Query *topquery, if (subquery->limitOffset != NULL || subquery->limitCount != NULL) return false; + /* Check point 2 */ + if (subquery->hasWindowFuncs) + return false; + /* Are we at top level, or looking at a setop component? */ if (subquery == topquery) { @@ -1093,6 +1100,12 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual, return false; /* + * It would be unsafe to push down window function calls, but at least + * for the moment we could never see any in a qual anyhow. + */ + Assert(!contain_window_function(qual)); + + /* * Examine all Vars used in clause; since it's a restriction clause, all * such Vars must refer to subselect output columns. */ |