Yesterday, Monty mentioned that he'd like to release MySQL 4.0.3 very soon. He was putting the finishing touches on the code to handle changing server configuration variables (like the size of the key buffer) on the fly. Today I got a chance to look at the docs that he's put together, and it's just what I've been waiting for!
Soon, we'll be able to do things like this:
SET GLOBAL key_buffer=256M
to change the key buffer's size without restarting the server. Cool. You'll be able to make both GLOBAL and SESSION (thread-specific).
Now I can embark on the project to build an auto-tuning engine that you can let loose on a server to make adjustments while the server is running. Should be a lot of fun (and work).
Oh, I'm sitting in Tim Bunce's "Advanced DBI" talk as I write this. We just learned (by way of Time questioning Monty) that MySQL 4.1 will provide high resolution timestamps. A code library already existing, it's just a matter of some integration work.