However, I think Aftab’s comment was getting to the root of the problem. One needs to be worried about long queries, but I would be equally worried about having a process having the power of a sledgehammer. In a case of a simple of a badly formed select query doing a table scan can be killed easily by any of these tools. But imagine an update query running in a MyISAM table. The update runs for a long time and the gets quashed by before all the updates are complete. Now I have committed the carnal sin of a DBA; I have left the database in an inconsistent state – definitely not cool.

Even in a transaction safe world, I do an insert/update, and half way through Brutus (my pt-kill process name :-)) comes and kills the process. Now the database has to do a rollback. We all know the rollback is an expensive process, so at this point I’m stuck between a rock and a hard place – also not cool.

The point I’m trying to make is that automated tools are excellent, but they come at a price. In the database word the price is a risk (small as it may be) that there may be unintended consequences. As long as we are ready to take those risks – bring them on.