# 第 52 章系统目录

目录

52.1.概述

52.2.pg_aggregate

52.3.pg_am

52.4.pg_amop

52.5.pg_ampproc

52.6.pg_attrdef

52.7.pg_attribute

52.8.pg_authid

52.9.pg_auth_members

52.10.pg_cast

52.11.pg_class

52.12.pg_collat​​ion

52.13.pg_constraint

52.14.pg_conversion

52.15.pg_database

52.16.pg_db_role_setting

52.17.pg_default_acl

52.18.pg_depend

52.19.pg_description

52.20.pg_enum

52.21.pg_event_trigger

52.22.pg_extension

52.23.pg_foreign_data_wrapper

52.24.pg_foreign_server

52.25.pg_foreign_table

52.26.pg_index

52.27.pg_inherits

52.28.pg_init_privs

52.29.pg_language

52.30.pg_largeobject

52.31.pg_largeobject_metadata

52.32.pg_namespace

52.33.pg_opclass

52.34.pg_operator

52.35.pg_opfamily

52.36.pg_partitioned_table

52.37.pg_policy

52.38.pg_proc

52.39.pg_publication

52.40.pg_publication_rel

52.41.pg_range

52.42.pg_replication_origin

52.43.pg_rewrite

52.44.pg_seclabel

52.45.pg_sequence

52.46.pg_shdepend

52.47.pg_shdescription

52.48.pg_shseclabel

52.49.pg_statistic

52.50.pg_statistic_ext

52.51.pg_statistic_ext_data

52.52.pg_subscription

52.53.pg_subscription_rel

52.54.pg_tablespace

52.55.pg_transform

52.56.pg_trigger

52.57.pg_ts_config

52.58.pg_ts_config_map

52.59.pg_ts_dict

52.60.pg_ts_parser

52.61.pg_ts_template

52.62.pg_type

52.63.pg_user_mapping

52.64.系统视图

52.65.pg_available_extensions

52.66.pg_available_extension_versions

52.67.pg_backend_memory_contexts

52.68.pg_config

52.69.pg_cursors

52.70.pg_file_settings

52.71.pg_group

52.72.pg_hba_file_rules

52.73.pg_indexes

52.74.pg_locks

52.75.pg_matviews

52.76.pg_policies

52.77.pg_prepared_statements

52.78.pg_prepared_xacts

52.79.pg_publication_tables

52.80.pg_replication_origin_status

52.81.pg_replication_slots

52.82.pg_roles

52.83.pg_rules

52.84.pg_seclabels

52.85.pg_sequences

52.86.pg_settings

52.87.pg_shadow

52.88.pg_shmem_allocations

52.89.pg_stats

52.90.pg_stats_ext

52.91.pg_stats_ext_exprs

52.92.pg_tables

52.93.pg_timezone_abbrevs

52.94.pg_timezone_names

52.95.pg_user

52.96.pg_user_mappings

52.97.pg_views

系统目录是关系数据库管理系统存储模式元数据的地方,例如有关表和列的信息以及内部簿记信息。PostgreSQL 的系统目录是常规表。您可以删除和重新创建表、添加列、插入和更新值,并以这种方式严重破坏您的系统。通常,不应手动更改系统目录,通常有 SQL 命令来执行此操作。(例如,创建数据库将一行插入pg_database目录——实际上是在磁盘上创建数据库。)对于特别深奥的操作有一些例外,但随着时间的推移,其中许多已经作为 SQL 命令提供,因此直接操作系统目录的需求不断减少。