Re: Server just hanging (More Information)

[Daniel Nichter]

IMHO, we're getting away from the real issue, which is: At seemingly random times, a good query goes bad and the process list shows it "Copying to tmp table." I don't think any amount of server/my.cnf tweaking fixes this. When I had this problem, the server was rock-solid otherwise, and configured as well as possible. I would say this issue is a MySQL bug perhaps, but without being able to systematically reproduce it, it's not worth reporting yet.

Thomas: Isn't a 100% key hit rate a good thing? If you're usually below this, and it jumps to 100 every time this problem happens, I think that's an interesting correlation, but I can't yet see how a high key hit rate would be directly related to MySQL copying data to a temp table.

If you can make some kind of test setup where this can be reproduced semi-reliably (at least once an hour), then what I'd do is start hacking the MySQL source code; run the problem on custom code with custom debugging output. If it's a test setup I can reproduce on my end, I'll do it and see what I can determine.