Providing PostgreSQL information to monitoring tools
PostgreSQL exposes a huge amount of information for monitoring. To expose that information securely, make sure your user has the predefined (default) pg_monitor role, which will give you all you need. Some sources say to expose the full contents of pg_stat_activity and similar restricted views, but be careful how and when you do this. Monitoring is important but so is security.
It's best to use historical monitoring information when all of it is available from the same place and on the same timescale. Most monitoring systems are designed for generic purposes while allowing application and system developers to integrate their specific checks with the monitoring infrastructure. This is possible through a plugin architecture. Adding new kinds of data inputs to them means installing a plugin. Sometimes, you may need to write or develop this plugin, but writing a plugin for something such as Cacti is easy. You just...
