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POImproving MySQL query performance when using SUM
 

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  1. POImproving MySQL query performance when using SUM
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    <p>I have a table of user-generated content that includes an ENUM format column for status. (Pending, Approved, Approved-auto, or Rejected) To keep en eye on the amount of recent content by status, I use the following query:</p> <pre><code>mysql&gt; SELECT DATE(dt_submitted) AS date, COUNT(*) AS count, SUM(IF(status='Approved', 1, 0)) as approved, SUM(IF(status='Approved-auto', 1, 0)) as approved_auto, SUM(IF(status='Rejected', 1, 0)) as rejected, SUM(IF(status='Pending', 1, 0)) as pending FROM post WHERE dt_submitted &gt; DATE_SUB(CURDATE(), INTERVAL 30 DAY) GROUP BY date; +------------+-------+----------+---------------+----------+---------+ | date | count | approved | approved_auto | rejected | pending | +------------+-------+----------+---------------+----------+---------+ | 2011-11-22 | 131 | 124 | 0 | 7 | 0 | | 2011-11-23 | 116 | 114 | 0 | 2 | 0 | ... | 2011-12-21 | 690 | 674 | 5 | 11 | 0 | | 2011-12-22 | 80 | 75 | 0 | 4 | 38 | +------------+-------+----------+---------------+----------+---------+ 31 rows in set (0.60 sec) </code></pre> <p>This is nearly perfect, but I'm picky and want to see if I can make it faster. (0.6 sec is slow on this server, and the table changes too often to worry about passing a static date to cache results.)</p> <p>If I EXPLAIN the query, it's not using any indexes (<code>status</code> is indexed). (Is this because it's referring to the temporary table created for the SUMs?)</p> <pre><code>explain SELECT DATE(dt_submitted) AS date, COUNT(*) AS count, SUM(IF(status='Approved', 1, 0)) as approved, SUM(IF(status='Approved-auto', 1, 0)) as approved_auto, SUM(IF(status='Rejected', 1, 0)) as rejected, SUM(IF(status='Pending', 1, 0)) as pending FROM post WHERE dt_submitted &gt; DATE_SUB(CURDATE(), INTERVAL 30 DAY) GROUP BY date; +----+-------------+-------+------+---------------+------+---------+------+--------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+--------+----------------------------------------------+ | 1 | SIMPLE | post | ALL | NULL | NULL | NULL | NULL | 529902 | Using where; Using temporary; Using filesort | +----+-------------+-------+------+---------------+------+---------+------+--------+----------------------------------------------+ 1 row in set (0.00 sec) </code></pre> <p>So is there anything I can do to optimize the table or rewrite the query to make this faster? Or is this query simply limited by the speed of available system resources?</p> <p>EDIT: <code>dt_submitted</code> was not indexed.</p>
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    1. USMike S.
    1. USMike S.
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    1. COCan you post your index create statements?
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      1. USMichael Fredrickson
    2. COHoly cow I'm an idiot. Was about to post the SHOW CREATE when I saw that dt_submitted is not, in fact, indexed. Creating the index cut the time down to 0.1 sec. (Now should I delete this question, or how do I best handle that?)
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    3. COcreate an answer for the question
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