PostgreSQL object hierarchy

Understanding the organization of the PostgreSQL database's logical objects helps with the understanding of object relations and interactions. PostgreSQL databases, roles, tablespaces, settings, and template languages have the same level of hierarchy, as shown in the following diagram:

All objects in the hierarchy are explained in detail in the following section.

Template databases

By default, when a database is created, it's cloned from a template database called template1. The template database contains a set of tables, views, and functions that are used to model the relation between the user-defined database objects. These tables, views, and functions are part of the system catalog...