No Silver Bullet

We just learned how tuning server options can dramatically improve performance. We’ve also seen in this chapter how to tune a particular query so it runs really fast. Tuning a query and tuning a server are often alternative solutions to performance problems. Is there any general rule about which kind of tuning you should start with?

I am afraid not. Tuning server options looks so promising that many people think finding and changing the right option will make mysqld run like a rocket. If you believe that too, I have to disappoint you: badly written queries will still be a drain on server resources. And you may enjoy good performance for a few hours after restarting the server only to see it decrease again, because every query will need a lot of resources and your caches will fill up. At times, the server will be inundated with millions of queries that want more and more resources.