You may want to split of your or conditions into a separate query, and use UNION.
On Tue, Aug 17, 2010 at 11:22 AM, Влад Р <vul...@gmail.com> wrote: > The main problem - if add in Join on `OR`-condition, select become > VERY slow. I realy > have to use this condition. > > -- -------------------------------------------------------- > -- > -- `tree_data` > -- > > CREATE TABLE IF NOT EXISTS `tree_data` ( > `id` int(11) NOT NULL AUTO_INCREMENT, > `pid` int(11) NOT NULL, > PRIMARY KEY (`id`), > ) ENGINE=MyISAM DEFAULT CHARSET=cp1251 AUTO_INCREMENT=869 ; > > testiong on 800 rows > > Simple tree join query > First QUERY is: > > SELECT > `l0`.`id` AS 'l0id', > `l0`.`pid` AS `l0pid` , > `l1`.`id` AS 'l1id', > `l1`.`pid` AS `l1pid` , > `l2`.`id` AS 'l2id', > `l2`.`pid` AS `l2pid` , > `l3`.`id` AS 'l3id', > `l3`.`pid` AS `l3pid` , > `l4`.`id` AS 'l4id', > `l4`.`pid` AS `l4pid` > FROM `tree_data` AS `l0` > LEFT JOIN `tree_data` as `l1` on (`l1`.`pid`=`l0`.`id`) > LEFT JOIN `tree_data` as `l2` on (`l2`.`pid`=`l1`.`id`) > LEFT JOIN `tree_data` as `l3` on (`l3`.`pid`=`l2`.`id`) > LEFT JOIN `tree_data` as `l4` on (`l4`.`pid`=`l3`.`id`) > WHERE `l0`.`pid` =0 > > id select_type table type possible_keys key key_len ref > rows Extra > 1 SIMPLE l0 ref pid pid 4 const 4 > 1 SIMPLE l1 ref pid pid 4 test.l0.id 9 > 1 SIMPLE l2 ref pid pid 4 test.l1.id 9 > 1 SIMPLE l3 ref pid pid 4 test.l2.id 9 > 1 SIMPLE l4 ref pid pid 4 test.l3.id 9 > > time execution is 0.0069. result 207 rows > > looking at other query > > SELECT > `l0`.`id` AS 'l0id', > `l0`.`pid` AS `l0pid` , > `l1`.`id` AS 'l1id', > `l1`.`pid` AS `l1pid` , > `l2`.`id` AS 'l2id', > `l2`.`pid` AS `l2pid` , > `l3`.`id` AS 'l3id', > `l3`.`pid` AS `l3pid` , > `l4`.`id` AS 'l4id', > `l4`.`pid` AS `l4pid` > FROM `tree_data` AS `l0` > LEFT JOIN `tree_data` as `l1` on (`l1`.`pid`=`l0`.`id` or `l1`.`pid`=100) > LEFT JOIN `tree_data` as `l2` on (`l2`.`pid`=`l1`.`id` or `l2`.`pid`=200) > LEFT JOIN `tree_data` as `l3` on (`l3`.`pid`=`l2`.`id` or `l3`.`pid`=300) > LEFT JOIN `tree_data` as `l4` on (`l4`.`pid`=`l3`.`id` or `l4`.`pid`=400) > WHERE `l0`.`pid` =0 > > And now execution time is 0.1455!!! > profiling gives: Sending data 0.137295 > And analize: > id select_type table type possible_keys key key_len ref > rows Extr > 1 SIMPLE l0 ref pid pid 4 const 4 > 1 SIMPLE l1 ALL pid NULL NULL NULL 800 > 1 SIMPLE l2 ALL pid NULL NULL NULL 800 > 1 SIMPLE l3 ALL pid NULL NULL NULL 800 > 1 SIMPLE l4 ALL pid NULL NULL NULL 800 > > And what will happen if there will be 10000 rows? > > (In real i using this `or` condition for selecting to the tree nodes > for current element id and id can be id from other nodes.) > -- Bier met grenadyn Is als mosterd by den wyn Sy die't drinkt, is eene kwezel Hy die't drinkt, is ras een ezel
