Thanks for replying. We have been trying it out for the last couple of weeks. It seems to work fine stopping surges or sudden spikes. But if you get a persistant user heavily abusing MySQL then it can cause issues. We found that when the heavy abuser gets restricted the MySQL process list built up to the max allowed, the account starts using more and more memory which in turns slows the clients site down until it eventually stops loading at all. But like I said, for sudded short spikes it does its job OK.