diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 47426d28eb5..bdd32718a08 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -7231,7 +7231,19 @@ remove_const(JOIN *join,ORDER *first_order, COND *cond, for (order=first_order; order ; order=order->next) { table_map order_tables=order->item[0]->used_tables(); - if (order->item[0]->with_sum_func) + if (order->item[0]->with_sum_func || + /* + If the outer table of an outer join is const (either by itself or + after applying WHERE condition), grouping on a field from such a + table will be optimized away and filesort without temporary table + will be used unless we prevent that now. Filesort is not fit to + handle joins and the join condition is not applied. We can't detect + the case without an expensive test, however, so we force temporary + table for all queries containing more than one table, ROLLUP, and an + outer join. + */ + (join->tables > 1 && join->rollup.state == ROLLUP::STATE_INITED && + join->outer_join)) *simple_order=0; // Must do a temp table to sort else if (!(order_tables & not_const_tables)) { |