diff options
Diffstat (limited to 'sql/sql_derived.cc')
| -rw-r--r-- | sql/sql_derived.cc | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc index 11d3a13b8b9..eb840e02a27 100644 --- a/sql/sql_derived.cc +++ b/sql/sql_derived.cc @@ -1271,7 +1271,8 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived) DBUG_RETURN(false); st_select_lex_unit *unit= derived->get_unit(); - st_select_lex *sl= unit->first_select(); + st_select_lex *first_sl= unit->first_select(); + st_select_lex *sl= first_sl; if (derived->prohibit_cond_pushdown) DBUG_RETURN(false); @@ -1419,7 +1420,24 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived) if (!extracted_cond_copy) continue; } - + + /* + Rename the columns of all non-first selects of a union to be compatible + by names with the columns of the first select. It will allow to use copies + of the same expression pushed into having clauses of different selects. + */ + if (sl != first_sl) + { + DBUG_ASSERT(sl->item_list.elements == first_sl->item_list.elements); + List_iterator_fast<Item> it(sl->item_list); + List_iterator_fast<Item> nm_it(unit->types); + Item * item; + while((item= it++)) + { + item->share_name_with(nm_it++); + } + } + /* Transform the references to the 'derived' columns from the condition pushed into the having clause of sl to make them usable in the new context |