diff options
Diffstat (limited to 'sql/item_subselect.cc')
| -rw-r--r-- | sql/item_subselect.cc | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc index e15fba78009..9494d1dc2ee 100644 --- a/sql/item_subselect.cc +++ b/sql/item_subselect.cc @@ -1817,6 +1817,21 @@ int subselect_single_select_engine::exec() thd->lex->current_select= save_select; DBUG_RETURN(join->error ? join->error : 1); } + if (!select_lex->uncacheable && thd->lex->describe && + !(join->select_options & SELECT_DESCRIBE) && + join->need_tmp && item->const_item()) + { + /* + Force join->join_tmp creation, because this subquery will be replaced + by a simple select from the materialization temp table by optimize() + called by EXPLAIN and we need to preserve the initial query structure + so we can display it. + */ + select_lex->uncacheable|= UNCACHEABLE_EXPLAIN; + select_lex->master_unit()->uncacheable|= UNCACHEABLE_EXPLAIN; + if (join->init_save_join_tab()) + DBUG_RETURN(1); /* purecov: inspected */ + } if (item->engine_changed) { DBUG_RETURN(1); @@ -1857,6 +1872,8 @@ int subselect_single_select_engine::exec() if (cond_guard && !*cond_guard) { /* Change the access method to full table scan */ + tab->save_read_first_record= tab->read_first_record; + tab->save_read_record= tab->read_record.read_record; tab->read_first_record= init_read_record_seq; tab->read_record.record= tab->table->record[0]; tab->read_record.thd= join->thd; @@ -1877,8 +1894,8 @@ int subselect_single_select_engine::exec() JOIN_TAB *tab= *ptab; tab->read_record.record= 0; tab->read_record.ref_length= 0; - tab->read_first_record= join_read_always_key_or_null; - tab->read_record.read_record= join_read_next_same_or_null; + tab->read_first_record= tab->save_read_first_record; + tab->read_record.read_record= tab->save_read_record; } executed= 1; thd->where= save_where; |