Only if you want to see duplicate rows :-)
On Tue, Aug 17, 2010 at 2:21 PM, Ananda Kumar <anandkl@stripped> wrote:
> use UNION ALL ..instead of UNION for better performance...
>
> On Tue, Aug 17, 2010 at 5:01 PM, Johan De Meersman <vegivamp@stripped
> >wrote:
>
> > 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.)
> > >
> >
> >
> >
> > --
> > Bier met grenadyn
> > Is als mosterd by den wyn
> > Sy die't drinkt, is eene kwezel
> > Hy die't drinkt, is ras een ezel
> >
>
--
Bier met grenadyn
Is als mosterd by den wyn
Sy die't drinkt, is eene kwezel
Hy die't drinkt, is ras een ezel
