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Re: Subquery with range uses filesort
Posted by: Rick James
Date: December 22, 2013 10:01AM

MySQL is internally structured such that the Parser, Optimizer, and a few more parts, are common code. The Engines (MyISAM, InnoDB, MEMORY) control the access to disk, etc.

A _correlated_ subquery cannot be turned directly into a JOIN. This is an SQL issue, not a MySQL issue.

Feel free to file a bug report about the poor performance. You can think of this forum as 'tier I' support, and bugs.mysql.com as 'tier II' support. (Paying Oracle, Percona, or SkySQL (etc), for support could be called Tier III.)

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