## 52.1. Overview

[Table 52.1](catalogs-overview.html#CATALOG-TABLE) 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 52.1. System Catalogs**

|                          Catalog Name                           |                                        Purpose                                        |
|-----------------------------------------------------------------|---------------------------------------------------------------------------------------|
|           [`pg_aggregate`](catalog-pg-aggregate.html)           |                                  aggregate functions                                  |
|                  [`pg_am`](catalog-pg-am.html)                  |                                relation access methods                                |
|                [`pg_amop`](catalog-pg-amop.html)                |                                access method operators                                |
|              [`pg_amproc`](catalog-pg-amproc.html)              |                            access method support functions                            |
|             [`pg_attrdef`](catalog-pg-attrdef.html)             |                                 column default values                                 |
|           [`pg_attribute`](catalog-pg-attribute.html)           |                             table columns (“attributes”)                              |
|              [`pg_authid`](catalog-pg-authid.html)              |                           authorization identifiers (roles)                           |
|        [`pg_auth_members`](catalog-pg-auth-members.html)        |                   authorization identifier membership relationships                   |
|                [`pg_cast`](catalog-pg-cast.html)                |                             casts (data type conversions)                             |
|               [`pg_class`](catalog-pg-class.html)               |                    tables, indexes, sequences, views (“relations”)                    |
|           [`pg_collation`](catalog-pg-collation.html)           |                            collations (locale information)                            |
|          [`pg_constraint`](catalog-pg-constraint.html)          |check constraints, unique constraints, primary key constraints, foreign key constraints|
|          [`pg_conversion`](catalog-pg-conversion.html)          |                            encoding conversion information                            |
|            [`pg_database`](catalog-pg-database.html)            |                        databases within this database cluster                         |
|     [`pg_db_role_setting`](catalog-pg-db-role-setting.html)     |                          per-role and per-database settings                           |
|         [`pg_default_acl`](catalog-pg-default-acl.html)         |                          default privileges for object types                          |
|              [`pg_depend`](catalog-pg-depend.html)              |                         dependencies between database objects                         |
|         [`pg_description`](catalog-pg-description.html)         |                     descriptions or comments on database objects                      |
|                [`pg_enum`](catalog-pg-enum.html)                |                           enum label and value definitions                            |
|       [`pg_event_trigger`](catalog-pg-event-trigger.html)       |                                    event triggers                                     |
|           [`pg_extension`](catalog-pg-extension.html)           |                                 installed extensions                                  |
|[`pg_foreign_data_wrapper`](catalog-pg-foreign-data-wrapper.html)|                           foreign-data wrapper definitions                            |
|      [`pg_foreign_server`](catalog-pg-foreign-server.html)      |                              foreign server definitions                               |
|       [`pg_foreign_table`](catalog-pg-foreign-table.html)       |                         additional foreign table information                          |
|               [`pg_index`](catalog-pg-index.html)               |                             additional index information                              |
|            [`pg_inherits`](catalog-pg-inherits.html)            |                              table inheritance hierarchy                              |
|          [`pg_init_privs`](catalog-pg-init-privs.html)          |                               object initial privileges                               |
|            [`pg_language`](catalog-pg-language.html)            |                            languages for writing functions                            |
|         [`pg_largeobject`](catalog-pg-largeobject.html)         |                             data pages for large objects                              |
|[`pg_largeobject_metadata`](catalog-pg-largeobject-metadata.html)|                              metadata for large objects                               |
|           [`pg_namespace`](catalog-pg-namespace.html)           |                                        schemas                                        |
|             [`pg_opclass`](catalog-pg-opclass.html)             |                            access method operator classes                             |
|            [`pg_operator`](catalog-pg-operator.html)            |                                       operators                                       |
|            [`pg_opfamily`](catalog-pg-opfamily.html)            |                            access method operator families                            |
|   [`pg_partitioned_table`](catalog-pg-partitioned-table.html)   |                       information about partition key of tables                       |
|              [`pg_policy`](catalog-pg-policy.html)              |                                 row-security policies                                 |
|                [`pg_proc`](catalog-pg-proc.html)                |                               functions and procedures                                |
|         [`pg_publication`](catalog-pg-publication.html)         |                         publications for logical replication                          |
|     [`pg_publication_rel`](catalog-pg-publication-rel.html)     |                            relation to publication mapping                            |
|               [`pg_range`](catalog-pg-range.html)               |                             information about range types                             |
|  [`pg_replication_origin`](catalog-pg-replication-origin.html)  |                            registered replication origins                             |
|             [`pg_rewrite`](catalog-pg-rewrite.html)             |                                  query rewrite rules                                  |
|            [`pg_seclabel`](catalog-pg-seclabel.html)            |                          security labels on database objects                          |
|            [`pg_sequence`](catalog-pg-sequence.html)            |                              information about sequences                              |
|            [`pg_shdepend`](catalog-pg-shdepend.html)            |                            dependencies on shared objects                             |
|       [`pg_shdescription`](catalog-pg-shdescription.html)       |                              comments on shared objects                               |
|          [`pg_shseclabel`](catalog-pg-shseclabel.html)          |                      security labels on shared database objects                       |
|           [`pg_statistic`](catalog-pg-statistic.html)           |                                  planner statistics                                   |
|       [`pg_statistic_ext`](catalog-pg-statistic-ext.html)       |                       extended planner statistics (definition)                        |
|  [`pg_statistic_ext_data`](catalog-pg-statistic-ext-data.html)  |                    extended planner statistics (built statistics)                     |
|        [`pg_subscription`](catalog-pg-subscription.html)        |                           logical replication subscriptions                           |
|    [`pg_subscription_rel`](catalog-pg-subscription-rel.html)    |                           relation state for subscriptions                            |
|          [`pg_tablespace`](catalog-pg-tablespace.html)          |                       tablespaces within this database cluster                        |
|           [`pg_transform`](catalog-pg-transform.html)           |               transforms (data type to procedural language conversions)               |
|             [`pg_trigger`](catalog-pg-trigger.html)             |                                       triggers                                        |
|           [`pg_ts_config`](catalog-pg-ts-config.html)           |                              text search configurations                               |
|       [`pg_ts_config_map`](catalog-pg-ts-config-map.html)       |                      text search configurations' token mappings                       |
|             [`pg_ts_dict`](catalog-pg-ts-dict.html)             |                               text search dictionaries                                |
|           [`pg_ts_parser`](catalog-pg-ts-parser.html)           |                                  text search parsers                                  |
|         [`pg_ts_template`](catalog-pg-ts-template.html)         |                                 text search templates                                 |
|                [`pg_type`](catalog-pg-type.html)                |                                      data types                                       |
|        [`pg_user_mapping`](catalog-pg-user-mapping.html)        |                         mappings of users to foreign servers                          |

