## 52.64. System Views

 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 37](information-schema.html)) 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 52.65](views-overview.html#VIEW-TABLE) 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 28.2](monitoring-stats.html#MONITORING-STATS-VIEWS-TABLE).

 Except where noted, all the views described here are read-only.

**Table 52.65. System Views**

|                                  View Name                                   |                               Purpose                               |
|------------------------------------------------------------------------------|---------------------------------------------------------------------|
|        [`pg_available_extensions`](view-pg-available-extensions.html)        |                        available extensions                         |
|[`pg_available_extension_versions`](view-pg-available-extension-versions.html)|                  available versions of extensions                   |
|     [`pg_backend_memory_contexts`](view-pg-backend-memory-contexts.html)     |                       backend memory contexts                       |
|                      [`pg_config`](view-pg-config.html)                      |                compile-time configuration parameters                |
|                     [`pg_cursors`](view-pg-cursors.html)                     |                            open cursors                             |
|               [`pg_file_settings`](view-pg-file-settings.html)               |               summary of configuration file contents                |
|                       [`pg_group`](view-pg-group.html)                       |                      groups of database users                       |
|              [`pg_hba_file_rules`](view-pg-hba-file-rules.html)              |    summary of client authentication configuration file contents     |
|                     [`pg_indexes`](view-pg-indexes.html)                     |                               indexes                               |
|                       [`pg_locks`](view-pg-locks.html)                       |                   locks currently held or awaited                   |
|                    [`pg_matviews`](view-pg-matviews.html)                    |                         materialized views                          |
|                    [`pg_policies`](view-pg-policies.html)                    |                              policies                               |
|         [`pg_prepared_statements`](view-pg-prepared-statements.html)         |                         prepared statements                         |
|              [`pg_prepared_xacts`](view-pg-prepared-xacts.html)              |                        prepared transactions                        |
|          [`pg_publication_tables`](view-pg-publication-tables.html)          |              publications and their associated tables               |
|   [`pg_replication_origin_status`](view-pg-replication-origin-status.html)   |information about replication origins, including replication progress|
|           [`pg_replication_slots`](view-pg-replication-slots.html)           |                    replication slot information                     |
|                       [`pg_roles`](view-pg-roles.html)                       |                           database roles                            |
|                       [`pg_rules`](view-pg-rules.html)                       |                                rules                                |
|                   [`pg_seclabels`](view-pg-seclabels.html)                   |                           security labels                           |
|                   [`pg_sequences`](view-pg-sequences.html)                   |                              sequences                              |
|                    [`pg_settings`](view-pg-settings.html)                    |                         parameter settings                          |
|                      [`pg_shadow`](view-pg-shadow.html)                      |                           database users                            |
|           [`pg_shmem_allocations`](view-pg-shmem-allocations.html)           |                      shared memory allocations                      |
|                       [`pg_stats`](view-pg-stats.html)                       |                         planner statistics                          |
|                   [`pg_stats_ext`](view-pg-stats-ext.html)                   |                     extended planner statistics                     |
|             [`pg_stats_ext_exprs`](view-pg-stats-ext-exprs.html)             |             extended planner statistics for expressions             |
|                      [`pg_tables`](view-pg-tables.html)                      |                               tables                                |
|            [`pg_timezone_abbrevs`](view-pg-timezone-abbrevs.html)            |                       time zone abbreviations                       |
|              [`pg_timezone_names`](view-pg-timezone-names.html)              |                           time zone names                           |
|                        [`pg_user`](view-pg-user.html)                        |                           database users                            |
|               [`pg_user_mappings`](view-pg-user-mappings.html)               |                            user mappings                            |
|                       [`pg_views`](view-pg-views.html)                       |                                views                                |

