In addition to the system catalogs, PostgreSQL
provides a number of built-in views. Some system views provide convenient
access to some commonly used queries on the system catalogs. Other views
provide access to internal server state.
The information schema (Chapter 31) provides
an alternative set of views which overlap the functionality of the system
views. Since the information schema is SQL-standard whereas the views
described here are PostgreSQL-specific,
it's usually better to use the information schema if it provides all
the information you need.
Table 42-34 lists the system views described here.
More detailed documentation of each view follows below.
There are some additional views that provide access to the results of
the statistics collector; they are described in Table 24-1.
Except where noted, all the views described here are read-only.