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Re: Simple 1-table query taking WAY to long.....
Posted by: Rick James
Date: January 24, 2012 01:09AM

PRIMARY KEY (`id`),
UNIQUE KEY `id_UNIQUE` (`id`),
Redundant. A PRIMARY KEY is a UNIQUE KEY; DROP the UNIQUE KEY.

KEY `another_index` (`feed_id`,`sent_date`,`parsed`) USING BTREE,
KEY `index_email_reports_group_by_feed_and_date` (`feed_id`,`sent_date`),
Remove the second; it is covered by the first.

KEY `fk_email_reports_1` (`feed_id`),
Remove it; two other indexes cover it.

Notice that it picked index_email_reports_on_sent_timestamp...

Nearly 80% of the table has feed_id = 110. Will that continue to be the case? Or is it an anomoly? I ask because the optimizer may be deciding that the WHERE clause, and the otherwise useful index on (`feed_id`,`sent_timestamp`) are rather useless.

> `sent_timestamp` datetime DEFAULT NULL,
Being NULLable does not help; it may even be causing the INDEX to be ignored.

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Re: Simple 1-table query taking WAY to long.....
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January 24, 2012 01:09AM


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