title: How transaction level isolation affects performace in autocommit mode in MySQL?
body: <p>I have a VBulletin 4.x forum running on my server. Some forum tables were converted into InnoDB for performance reasons according to <a href="http://www.vbulletinguru.com/2010/part-2-vb4mance-vbulletin4-optimization-basic-guide-to-innodb-conversion/" rel="nofollow noreferrer">this instruction</a>. Forum itself does not use transactions (no START TRANSACTION or BEGIN WORK in source code) at all and InnoDB tables are used just to prevent tables from locking on UPDATE queries. Forum is functioning in autocommit mode of course.</p>
  
  <p>Do I understand correctly, that I can change the default server transaction isolation level into <strong>READ UNCOMMITED</strong> in this case and get some performance gains this way? </p>