In this chapter, you will find recipes for some common monitoring and diagnosis actions you will want to do inside your database. They are meant to answer specific questions that you often face when using PostgreSQL.
Databases are not isolated entities. They live on computer hardware using CPUs, RAM, and disk subsystems. Users access databases using networks. Depending on the setup, databases themselves may need network resources to function in any of the following ways: performing some authentication checks when users log in, using disks that are mounted over the network (not generally recommended), or making remote function calls to other databases.
This means that monitoring only the database is not enough