System Tables

A great deal of data is stored in POSTGRESQL system tables. The names of these tables begin with pg_. The tables contain information about data types, functions , operators , databases, users, and groups. Table  shows the most commonly used tables.

 

Table: Commonly used system tables

Table	Contents
pg_aggregate	aggregates
pg_attribute	columns
pg_class	tables
pg_database	databases
pg_description	comments
pg_group	groups
pg_index	indexes
pg_log	transaction status
pg_operator	operators
pg_proc	functions
pg_rewrite	rules  and views
pg_shadow	users
pg_trigger	triggers
pg_type	types

The pg_log table is a binary file rather than a real table. The pg_shadow table contains user passwords and is not visible to ordinary users. The pg_user table (not listed in Table ) is a view of pg_shadow that does not display the password field. Several other system views are available as well. Most system tables are joined using OIDs  (see Section ). Psql's \dS command lists all system tables and views.