Another question: why is type='range' for sort_intersect? We have type=index_merge for intersect and [sort]_union, so it seems rather confusing that we have type=range for sort_intersect? ----- Forwarded message from Sergey Petrunya ----- Date: Wed, 19 Jan 2011 11:11:14 +0300 From: Sergey Petrunya To: igor@askmonty.org Cc: Maria Developers Subject: No "Using index" support in sort-intersect - intentional? Hello Igor, I was looking at sort-intersect and noticed the following: Consider this table: CREATE TABLE `t1` ( `k1` int(11) DEFAULT NULL, `k2` int(11) DEFAULT NULL, `filler` char(100) DEFAULT NULL, KEY `k1` (`k1`), KEY `k2` (`k2`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; Let's try a sort-intersect query: MariaDB [timerge1]> EXPLAIN select 1 from t1 where k1<30 and k2 < 30\G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: t1 type: range possible_keys: k1,k2 key: k1,k2 key_len: 5,5 ref: NULL rows: 1 Extra: Using sort_intersect(k1,k2); Using where 1 row in set (0.01 sec) The query doesn't use any columns not covered by the used indexes, however, we don't see "using index". Analogous ROR-intersect query will use "Using index": MariaDB [timerge1]> EXPLAIN select 1 from t1 where k1=30 and k2 = 30\G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: t1 type: index_merge possible_keys: k1,k2 key: k1,k2 key_len: 5,5 ref: NULL rows: 1 Extra: Using intersect(k1,k2); Using where; Using index 1 row in set (0.00 sec) BR Sergey -- Sergey Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog ----- End forwarded message ----- -- BR Sergey -- Sergey Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog