Understanding MySQL Internals

Understanding MySQL Internals. By Sasha Pachev, O’Reilly 2007. Page count: about 227 pages. (Here’s a link to the publisher’s site).

I should have read this book a long time ago, and it’s my loss that I didn’t. Although the title makes it sound like it should only benefit those who’ll be changing the MySQL server’s own code, that’s not true. To the contrary, at least parts of this book should be required reading for DBAs and developers who use MySQL, after they gain a moderate level of familiarity with how to use the server.

The book does indeed start off …

The best overall method of performance optimization is optimization for response time. Users care about response time, not load average or cache hit ratios. The job of a system is to accept some request and do the required work, and deliver a result. The time elapsed between the request and the result is the response time.

Methods of Response Time Optimization

Not all optimization methods are created equal. Here are a few I see commonly.

• No method. Most people simply have no method of performance optimization at all. They just look for things that look “bad” and try to make them look “better.” In the MySQL database world, the classic example is trying to improve a cache hit ratio. This is utter folly, and doesn’t become any less stupid no matter how many times it is taught and repeated.
• Server Load Reduction. One step up from that is to try …