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 <vuliad@stripped> 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.)
>
--
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