April 16, 2014

Quick tip: how to convert tables to InnoDB

I use Maatkit for a lot of grunt work and thought you might appreciate this quick tip. Suppose you have a bazillion tables to convert from MyISAM to InnoDB, but they are mixed in with other tables that are already InnoDB, or are another storage engine that you don’t want to touch.

Here’s a bonus tip, while I’m at it. I had a client a while back whose application creates tables as needed, so they had about 90,000 tables in a bunch of different databases, all named things like user_123_456_friends. I wanted to add an index to them — but not to the ones named friends_123_456_user.

Boy, is that a lot easier than adding indexes to 90k tables by hand!

About Baron Schwartz

Baron is the lead author of High Performance MySQL. He maintains a personal blog at Xaprb. Follow him at @xaprb or connect with him on LinkedIn.


  1. FraggeR says:

    Sounds interesting,

    but, one questions …. if you are allowed to answer it….. 90k tables for what ??

    isnt this a perfomance break itself ?

  2. Oh yeah, that was definitely a design flaw :-) This site was in serious trouble. But that’s another story.

  3. kostja says:

    You could write a stored procedure that uses dynamic sql for the same thing. ALTER TABLE works in dynamic sql.

  4. If your environment was all MyISAM earlier and you used skip-innodb in your my.cnf, make sure you comment or remove it before converting using Maatkit or by manually using ALTER TABLE

  5. john says:


    how can I skip table ?

Speak Your Mind