---
title: "Overview"
id: views-overview
pg_version: "20devel"
---

<a id="views-overview"></a>

## 53.1. Overview

[Table 53.1](views-overview.md#view-table) lists the system views. More detailed documentation of each catalog follows below. Except where noted, all the views described here are read-only. 

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**System Views**

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