diff options
| author | gkodinov/kgeorge@macbook.local <> | 2006-10-09 19:51:41 +0400 |
|---|---|---|
| committer | gkodinov/kgeorge@macbook.local <> | 2006-10-09 19:51:41 +0400 |
| commit | 13633864bbea56928291443bdafa00dec0be6825 (patch) | |
| tree | 073ea6f39d3e03cc1ad7bb39aefbe30ed6f415ab /sql/sql_select.cc | |
| parent | dead2e0f147017e85e4934fb65103adc464041ec (diff) | |
| download | mariadb-git-13633864bbea56928291443bdafa00dec0be6825.tar.gz | |
Bug #22781: SQL_BIG_RESULT fails to influence sort plan
Currently SQL_BIG_RESULT is checked only at compile time.
However, additional optimizations may take place after
this check that change the sort method from 'filesort'
to sorting via index. As a result the actual plan
executed is not the one specified by the SQL_BIG_RESULT
hint. Similarly, there is no such test when executing
EXPLAIN, resulting in incorrect output.
The patch corrects the problem by testing for
SQL_BIG_RESULT both during the explain and execution
phases.
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index b328d9162d5..e9c282c1d24 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -1399,7 +1399,8 @@ JOIN::exec() simple_order= simple_group; skip_sort_order= 0; } - if (order && + if (order && + (order != group_list || !(select_options & SELECT_BIG_RESULT)) && (const_tables == tables || ((simple_order || skip_sort_order) && test_if_skip_sort_order(&join_tab[const_tables], order, @@ -11995,11 +11996,17 @@ create_sort_index(THD *thd, JOIN *join, ORDER *order, table= tab->table; select= tab->select; - if (test_if_skip_sort_order(tab,order,select_limit,0)) + /* + When there is SQL_BIG_RESULT do not sort using index for GROUP BY, + and thus force sorting on disk. + */ + if ((order != join->group_list || + !(join->select_options & SELECT_BIG_RESULT)) && + test_if_skip_sort_order(tab,order,select_limit,0)) DBUG_RETURN(0); if (!(sortorder=make_unireg_sortorder(order,&length))) goto err; /* purecov: inspected */ - /* It's not fatal if the following alloc fails */ + table->sort.io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE), MYF(MY_WME | MY_ZEROFILL)); table->status=0; // May be wrong if quick_select |