diff options
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index af3ad782ee3..36a15841065 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -9754,7 +9754,7 @@ bool JOIN::rollup_init() for (j=0 ; j < fields_list.elements ; j++) rollup.fields[i].push_back(rollup.null_items[i]); } - List_iterator_fast<Item> it(all_fields); + List_iterator<Item> it(all_fields); Item *item; while ((item= it++)) { @@ -9767,6 +9767,32 @@ bool JOIN::rollup_init() { item->maybe_null= 1; found_in_group= 1; + if (item->const_item()) + { + /* + For ROLLUP queries each constant item referenced in GROUP BY list + is wrapped up into an Item_func object yielding the same value + as the constant item. The objects of the wrapper class are never + considered as constant items and besides they inherit all + properties of the Item_result_field class. + This wrapping allows us to ensure writing constant items + into temporary tables whenever the result of the ROLLUP + operation has to be written into a temporary table, e.g. when + ROLLUP is used together with DISTINCT in the SELECT list. + Usually when creating temporary tables for a intermidiate + result we do not include fields for constant expressions. + */ + Item* new_item= new Item_func_rollup_const(item); + if (!new_item) + return 1; + new_item->fix_fields(thd,0, (Item **) 0); + thd->change_item_tree(it.ref(), new_item); + for (ORDER *tmp= group_tmp; tmp; tmp= tmp->next) + { + if (*tmp->item == item) + thd->change_item_tree(tmp->item, new_item); + } + } } } if (item->type() == Item::FUNC_ITEM && !found_in_group) |