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Note: The following description applies both to Postgres-XC and PostgreSQL if not described explicitly.
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 33) 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 45-54 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 26-1.
Except where noted, all the views described here are read-only.
Table 45-54. System Views
| View Name | Purpose |
|---|---|
| pg_available_extensions | available extensions |
| pg_available_extension_versions | available versions of extensions |
| pg_cursors | open cursors |
| pg_group | groups of database users |
| pg_indexes | indexes |
| pg_locks | currently held locks |
| pg_prepared_statements | prepared statements |
| pg_prepared_xacts | prepared transactions |
| pg_roles | database roles |
| pg_rules | rules |
| pg_seclabels | security labels |
| pg_settings | parameter settings |
| pg_shadow | database users |
| pg_stats | planner statistics |
| pg_tables | tables |
| pg_timezone_abbrevs | time zone abbreviations |
| pg_timezone_names | time zone names |
| pg_user | database users |
| pg_user_mappings | user mappings |
| pg_views | views |