content/data-base/Avoid Shared Locks from Subqueries When Possible.md

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Title: "Avoid Shared Locks from Subqueries When Possible" Date: 2017-11-14 15:48:03 Categories: [data base] tags: [mysql, mariadb, percona]

Authors: sedlav

In this blog post, we’ll look at how to avoid shared locks from subqueries.

I’m pretty sure most of you have seen an UPDATE statement matching rows returned from a SELECT query:

update ibreg set k=1 where id in (select id from ibcmp where id > 90000);

This query, when executed with

autocommit=1

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