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POAnyone care to help optimize a MySQL query?
 

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  1. POAnyone care to help optimize a MySQL query?
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    <p>Here's the query:</p> <pre><code>SELECT COUNT(*) AS c, MAX(`followers_count`) AS max_fc, MIN(`followers_count`) AS min_fc, MAX(`following_count`) AS max_fgc, MIN(`following_count`) AS min_fgc, SUM(`followers_count`) AS fc, SUM(`following_count`) AS fgc, MAX(`updates_count`) AS max_uc, MIN(`updates_count`) AS min_uc, SUM(`updates_count`) AS uc FROM `profiles` WHERE `twitter_id` IN (SELECT `followed_by` FROM `relations` WHERE `twitter_id` = 123); </code></pre> <p>The two tables are <code>profiles</code> and <code>relations</code>. Both have over 1,000,000 rows, InnoDB engine. Both have indexes on <code>twitter_id</code>, <code>relations</code> has an extra index on (<code>twitter_id</code>, <code>followed_by</code>). The query is taking over 6 seconds to execute, this really frustrates me. I know that I can JOIN this somehow, but my MySQL knowledge is not so cool, that's why I'm asking for your help.</p> <p>Thanks in advance everyone =)</p> <p>Cheers, K ~</p> <p><strong>Updated</strong></p> <p>Okay I managed to get down to 2,5 seconds. I used INNER JOIN and added the three index pairs. Here's the EXPLAIN results:</p> <pre><code>id, select_type, table, type, possible_keys, key, key_len, ref, rows, Extra 1, 'SIMPLE', 'r', 'ref', 'relation', 'relation', '4', 'const', 252310, 'Using index' 1, 'SIMPLE', 'p', 'ref', 'PRIMARY,twiter_id,id_fc,id_fgc,id_uc', 'id_uc', '4', 'follerme.r.followed_by', 1, '' </code></pre> <p>Hope this helps.</p> <p><strong>Another update</strong></p> <p>Here are the SHOW CREATE TABLE statements for both tables:</p> <pre><code>CREATE TABLE `profiles` ( `twitter_id` int(10) unsigned NOT NULL, `screen_name` varchar(45) NOT NULL default '', `followers_count` int(10) unsigned default NULL, `following_count` int(10) unsigned default NULL, `updates_count` int(10) unsigned default NULL, `location` varchar(45) default NULL, `bio` varchar(160) default NULL, `url` varchar(255) default NULL, `image` varchar(255) default NULL, `registered` int(10) unsigned default NULL, `timestamp` int(10) unsigned default NULL, `relations_timestamp` int(10) unsigned default NULL, PRIMARY KEY USING BTREE (`twitter_id`,`screen_name`), KEY `twiter_id` (`twitter_id`), KEY `screen_name` USING BTREE (`screen_name`,`twitter_id`), KEY `id_fc` (`twitter_id`,`followers_count`), KEY `id_fgc` (`twitter_id`,`following_count`), KEY `id_uc` (`twitter_id`,`updates_count`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 CREATE TABLE `relations` ( `id` int(10) unsigned NOT NULL auto_increment, `twitter_id` int(10) unsigned NOT NULL default '0', `followed_by` int(10) unsigned default NULL, `timestamp` int(10) unsigned default NULL, PRIMARY KEY USING BTREE (`id`,`twitter_id`), UNIQUE KEY `relation` (`twitter_id`,`followed_by`) ) ENGINE=InnoDB AUTO_INCREMENT=1209557 DEFAULT CHARSET=utf8 </code></pre> <p>Wow, what a mess =) Sorry!</p>
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