Nobody cares about database logging, but I really recommend enabling them to see what is happening behind the scenes (specially for web applications).
To enable on PostgreSQL (and be compatible with OSSEC):
To enable the generic Query log on MySQL (the error log in on by default), you need to start MySQL with –log:
The best option is to modify /etc/init.d/mysqld (if using Centos) and inside the –log in there.
Nothing new, but I was searching for this information online and couldn’t find much info.