Been at the MySQL conference the last few days, and I have to say, I’m really blown away by MySQL 5.5.4’s improvements. Last year I keynoted and I begged Oracle on stage to realize that MySQL and InnoDB under one roof represented opportunity. It’s clear they heard the community – this is some serious progress, and right when we needed it.
Jeremy Zawodny’s blog post covers most of the stuff I’m really excited about, and there are some great detailed technical slides here and here, but I wanted to go into a little more detail on one important improvment: We’ve been plagued by MySQL’s undo slot limits for an awfully long time. Basically, you could have 512 INSERT transactions and 512 UPDATE transactions running at once, for a grand total of 1024. If you use INSERT … ON DUPLICATE KEY UPDATE, though, it takes two of those spots, meaning you get 512 concurrent transactions. On modern hardware, it’s trivially easy to hit this limit.
I’ve had an Enterprise support ticket open for years on the issue, there’s been a MySQL bug for a long time, and there was basically no movement. In fact, I’d gotten so frustrated about this issue, I’d basically decided this year was our last year of Enterprise MySQL support. It was one of the sole reasons we paid for support for the last few years – the promise that a fix was just around the corner. I felt good about voting with my dollars, and contributing back to a core technology we depend on, but enough was enough.
Lo and behold, it’s fixed! You can now have a whopping 128K transactions in flight. Best of all, it’s far more performant than it used to be! And craziest of all? If you run 5.5.4 on a database, then roll back to some older release, the change still takes effect. Backwards bug and performance fixing – that’s a new one on me.
THANK YOU ORACLE!
Shameless plug – we’re hiring. And it’s a blast.
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