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Asked: 2026-05-17T22:24:40+00:00

In our production database, we ran the following pseudo-code SQL batch query running every

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In our production database, we ran the following pseudo-code SQL batch query running every hour:

INSERT INTO TemporaryTable
    (SELECT FROM HighlyContentiousTableInInnoDb
     WHERE allKindsOfComplexConditions are true)

Now this query itself does not need to be fast, but I noticed it was locking up HighlyContentiousTableInInnoDb, even though it was just reading from it. Which was making some other very simple queries take ~25 seconds (that’s how long that other query takes).

Then I discovered that InnoDB tables in such a case are actually locked by a SELECT! https://www.percona.com/blog/2006/07/12/insert-into-select-performance-with-innodb-tables/

But I don’t really like the solution in the article of selecting into an OUTFILE, it seems like a hack (temporary files on filesystem seem sucky). Any other ideas? Is there a way to make a full copy of an InnoDB table without locking it in this way during the copy. Then I could just copy the HighlyContentiousTable to another table and do the query there.

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1 Answer

  1. Editorial Team

    The answer to this question is much easier now:
    – Use Row Based Replication and Read Committed isolation level.

    The locking you were experiencing disappears.

    Longer explaination: http://harrison-fisk.blogspot.com/2009/02/my-favorite-new-feature-of-mysql-51.html

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