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POoptimize mysql count query
 

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    <p>Is there a way to optimize this further or should I just be satisfied that it takes 9 seconds to count 11M rows ?</p> <pre><code>devuser@xcmst &gt; mysql --user=user --password=pass -D marctoxctransformation -e "desc record_updates" +--------------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+----------+------+-----+---------+-------+ | record_id | int(11) | YES | MUL | NULL | | | date_updated | datetime | YES | MUL | NULL | | +--------------+----------+------+-----+---------+-------+ devuser@xcmst &gt; date; mysql --user=user --password=pass -D marctoxctransformation -e "select count(*) from record_updates where date_updated &gt; '2009-10-11 15:33:22' "; date Thu Dec 9 11:13:17 EST 2010 +----------+ | count(*) | +----------+ | 11772117 | +----------+ Thu Dec 9 11:13:26 EST 2010 devuser@xcmst &gt; mysql --user=user --password=pass -D marctoxctransformation -e "explain select count(*) from record_updates where date_updated &gt; '2009-10-11 15:33:22' " +----+-------------+----------------+-------+--------------------------------------------------------+--------------------------------------------------------+---------+------+----------+--------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------------+-------+--------------------------------------------------------+--------------------------------------------------------+---------+------+----------+--------------------------+ | 1 | SIMPLE | record_updates | index | idx_marctoxctransformation_record_updates_date_updated | idx_marctoxctransformation_record_updates_date_updated | 9 | NULL | 11772117 | Using where; Using index | +----+-------------+----------------+-------+--------------------------------------------------------+--------------------------------------------------------+---------+------+----------+--------------------------+ devuser@xcmst &gt; mysql --user=user --password=pass -D marctoxctransformation -e "show keys from record_updates" +----------------+------------+--------------------------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | +----------------+------------+--------------------------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+ | record_updates | 1 | idx_marctoxctransformation_record_updates_date_updated | 1 | date_updated | A | 2416 | NULL | NULL | YES | BTREE | | | record_updates | 1 | idx_marctoxctransformation_record_updates_record_id | 1 | record_id | A | 11772117 | NULL | NULL | YES | BTREE | | +----------------+------------+--------------------------------------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+ </code></pre> <p><strong>UPDATE</strong> - my solution is here: <a href="http://code.google.com/p/xcmetadataservicestoolkit/wiki/ResumptionToken">http://code.google.com/p/xcmetadataservicestoolkit/wiki/ResumptionToken</a></p>
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    1. COwhat's the engine - MyISAM or InnoDB?
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    2. COGranted, you have 11 million rows in the table, but on average, how many entries are actually being updated in any given day? OR, is the 11 million rows, the number that ARE being updated. If 11 million updates per day, I would go with a summary table.
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    3. COengine is myisam. summary table won't work for this - data is changing and queries could be anything (by the second)
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