diff options
Diffstat (limited to 'src/backend/optimizer')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 62fa2c8b0da..64822141b78 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -2278,6 +2278,17 @@ standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels) * thereby changing the partition contents and thus the window functions' * results for rows that remain. * + * 5. If the subquery has nonempty grouping sets, we cannot push down any + * quals. The concern here is that a qual referencing a "constant" grouping + * column could get constant-folded, which would be improper because the value + * is potentially nullable by grouping-set expansion. This restriction could + * be removed if we had a parsetree representation that shows that such + * grouping columns are not really constant. (There are other ideas that + * could be used to relax this restriction, but that's the approach most + * likely to get taken in the future. Note that there's not much to be gained + * so long as subquery_planner can't move HAVING clauses to WHERE within such + * a subquery.) + * * In addition, we make several checks on the subquery's output columns to see * if it is safe to reference them in pushed-down quals. If output column k * is found to be unsafe to reference, we set safetyInfo->unsafeColumns[k] @@ -2322,6 +2333,10 @@ subquery_is_pushdown_safe(Query *subquery, Query *topquery, if (subquery->limitOffset != NULL || subquery->limitCount != NULL) return false; + /* Check point 5 */ + if (subquery->groupClause && subquery->groupingSets) + return false; + /* Check points 3 and 4 */ if (subquery->distinctClause || subquery->hasWindowFuncs) safetyInfo->unsafeVolatile = true; |