A very quick entry today, life seems to be so busy at the moment but I have to write this down before I forget. Today I had a weird situation where mysql was consuming a lot of resources but didn't seem to be actually getting anywhere, as if something was "stuck" inside it. Using the processlist I was able to diagnose the problem. From the command line just run:

show processlist;

If you're a phpMyAdmin user, then there's a link for "processes" on the front page of your installation. Give it a try when things seem to be taking longer than they should!