Table of Contents
pg_aggregatepg_ampg_amoppg_amprocpg_attrdefpg_attributepg_authidpg_auth_memberspg_autovacuumpg_castpg_classpg_constraintpg_conversionpg_databasepg_dependpg_descriptionpg_indexpg_inheritspg_languagepg_largeobjectpg_listenerpg_namespacepg_opclasspg_operatorpg_pltemplatepg_procpg_rewritepg_shdependpg_statisticpg_tablespacepg_triggerpg_typepg_grouppg_indexespg_lockspg_prepared_xactspg_rolespg_rulespg_settingspg_shadowpg_statspg_tablespg_userpg_views The system catalogs are the place where a relational database
management system stores schema metadata, such as information about
tables and columns, and internal bookkeeping information.
PostgreSQL's system catalogs are regular
tables. You can drop and recreate the tables, add columns, insert
and update values, and severely mess up your system that way.
Normally, one should not change the system catalogs by hand, there
are always SQL commands to do that. (For example, CREATE
DATABASE inserts a row into the
pg_database catalog [mdash ] and actually
creates the database on disk.) There are some exceptions for
particularly esoteric operations, such as adding index access methods.
Table 42.1, “System Catalogs” lists the system catalogs. More detailed documentation of each catalog follows below.
Most system catalogs are copied from the template database during database creation and are thereafter database-specific. A few catalogs are physically shared across all databases in a cluster; these are noted in the descriptions of the individual catalogs.
Table 42.1. System Catalogs
| Catalog Name | Purpose |
|---|---|
pg_aggregate |
aggregate functions |
pg_am |
index access methods |
pg_amop |
access method operators |
pg_amproc |
access method support procedures |
pg_attrdef |
column default values |
pg_attribute |
table columns (“attributes”) |
pg_authid |
authorization identifiers (roles) |
pg_auth_members |
authorization identifier membership relationships |
pg_autovacuum |
per-relation autovacuum configuration parameters |
pg_cast |
casts (data type conversions) |
pg_class |
tables, indexes, sequences, views (“relations”) |
pg_constraint |
check constraints, unique constraints, primary key constraints, foreign key constraints |
pg_conversion |
encoding conversion information |
pg_database |
databases within this database cluster |
pg_depend |
dependencies between database objects |
pg_description |
descriptions or comments on database objects |
pg_index |
additional index information |
pg_inherits |
table inheritance hierarchy |
pg_language |
languages for writing functions |
pg_largeobject |
large objects |
pg_listener |
asynchronous notification support |
pg_namespace |
schemas |
pg_opclass |
index access method operator classes |
pg_operator |
operators |
pg_pltemplate |
template data for procedural languages |
pg_proc |
functions and procedures |
pg_rewrite |
query rewrite rules |
pg_shdepend |
dependencies on shared objects |
pg_statistic |
planner statistics |
pg_tablespace |
tablespaces within this database cluster |
pg_trigger |
triggers |
pg_type |
data types |