## 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 |