MySQL Performance Monitoring I already have system availability monitoring for all my MySQL instances in Nagios.  I'm looking to get some trending monitoring going for activity. It'd be nice to see how all the information_schema stats trend over time, to help identify sources of problems etc.

I've seen Cacti exists and seems pretty popular.

What have your experiences with Cacti been (pros/cons)?

Are there any other common solutions I should investigate?
If  you're looking for graphs, Cacti (or Munin) will work. I've personally only used Munin.

However, I wouldn't put much stock in graphs to troubleshoot problems that arise. If it's showing in the graphs, it's been going on too long.

I would get familiar with the maatkit or percona tools (I think percona is a fork of maatkit) for trouble shooting problems.