If you've ever been responsible for a busy Magento store, you will inevitably run into issues with the various log_* tables getting too big and caning your database.

In theory the Magento cron subsystem should keep a lid on these tables growing too big, but I avoid using Magento cron, preferring to handle that myself directly via crontab tasks.

The other option is to write your own table cleaning script (or copy one from somewhere), and this will work too. But it's annoying, if you don't want this log data, why write it in the first place.

So my solution is to disable it by removing the observer events that perform the logging.

I have this in my local.xml which takes precedence over other nodes in the config and therefore overwrites them. Here, by setting the observer to be the string 'disabled', the existing observer event is removed and replaced with something that will never be fired.

Now, you don't need to worry about periodically cleaning out your database, nor do you need to fear a 3am text message from your production DB servers screaming about the disk being full...