database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-10-12 12:25:37 +03:00
Code Activity

Fixed bug mdev-5028.

Browse Source 
Apparently in a general case a short-cut for the distinct optimization
is invalid if join buffers are used to join tables after the tables whose
values are to selected.
This commit is contained in:
Igor Babaev
2013-10-02 17:59:56 -07:00
parent ec7da1561e
commit 00816a964f
5 changed files with 179 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
sql/sql_select.cc
View File

@@ -1811,9 +1811,10 @@ int JOIN::init_execution()
JOIN_TAB *last_join_tab= join_tab + top_join_tab_count - 1;
do
{
if (used_tables & last_join_tab->table->map)
if (used_tables & last_join_tab->table->map ||
last_join_tab->use_join_cache)
break;
last_join_tab->not_used_in_distinct=1;
last_join_tab->shortcut_for_distinct= true;
} while (last_join_tab-- != join_tab);
/* Optimize "select distinct b from t1 order by key_part_1 limit #" */
if (order && skip_sort_order)
@@ -7983,7 +7984,7 @@ JOIN::make_simple_join(JOIN *parent, TABLE *temp_table)
join_tab->last_inner= 0;
join_tab->first_unmatched= 0;
join_tab->ref.key = -1;
join_tab->not_used_in_distinct=0;
join_tab->shortcut_for_distinct= false;
join_tab->read_first_record= join_init_read_record;
join_tab->preread_init_done= FALSE;
join_tab->join= this;
@@ -16223,7 +16224,7 @@ static enum_nested_loop_state
evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
int error)
{
bool not_used_in_distinct=join_tab->not_used_in_distinct;
bool shortcut_for_distinct= join_tab->shortcut_for_distinct;
ha_rows found_records=join->found_records;
COND *select_cond= join_tab->select_cond;
bool select_cond_result= TRUE;
@@ -16362,7 +16363,7 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
was not in the field list; In this case we can abort if
we found a row, as no new rows can be added to the result.
*/
if (not_used_in_distinct && found_records != join->found_records)
if (shortcut_for_distinct && found_records != join->found_records)
DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS);
}
else