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POMySQL 1 millon row query speed
 

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    <p>I'm having trouble getting a decent query time out of a large MySQL table, currently its taking over 20 seconds. The problem lies in the GROUP BY as MySQL needs to run a filesort but I don't see how I can get around this</p> <p><strong>QUERY</strong>:</p> <pre><code>SELECT play_date, COUNT(DISTINCT(email)) AS count FROM log WHERE type = 'play' AND play_date BETWEEN '2009-02-23' AND '2009-02-24' GROUP BY play_date ORDER BY play_date desc </code></pre> <p><strong>EXPLAIN</strong>:</p> <pre><code>id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE log ALL type,type_2 NULL NULL NULL 530892 Using where; Using filesort </code></pre> <p><strong>TABLE STRUCTURE</strong></p> <pre><code>CREATE TABLE IF NOT EXISTS `log` ( `id` int(11) NOT NULL auto_increment, `email` varchar(255) NOT NULL, `type` enum('played','reg','friend') NOT NULL, `timestamp` timestamp NOT NULL default CURRENT_TIMESTAMP, `play_date` date NOT NULL, `email_refer` varchar(255) NOT NULL, `remote_addr` varchar(15) NOT NULL, PRIMARY KEY (`id`), KEY `email` (`email`), KEY `type` (`type`), KEY `email_refer` (`email_refer`), KEY `type_2` (`type`,`timestamp`,`play_date`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=707859 ; </code></pre> <p>If anyone knows how I could improve the speed I would be very greatful</p> <p>Tom</p> <p><strong><em>EDIT</em></strong></p> <p>I've added the new index with just play_date and type but MySQL refuses to use it</p> <pre><code>id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE log ALL play_date NULL NULL NULL 801647 Using where; Using filesort </code></pre> <p>This index was created using ALTER TABLE <code>log</code> ADD INDEX (<code>type</code>, <code>play_date</code>);</p>
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    1. COPlease post how eactly did you create the index on `(type, play_date)`
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    2. COALTER TABLE `log` ADD INDEX (`type`, `play_date`);
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