PostgreSQL 9.6.0 手册
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章 50. 系统目录

目录
50.1. 概述
50.2. pg_aggregate
50.3. pg_am
50.4. pg_amop
50.5. pg_amproc
50.6. pg_attrdef
50.7. pg_attribute
50.8. pg_authid
50.9. pg_auth_members
50.10. pg_cast
50.11. pg_class
50.12. pg_collation
50.13. pg_constraint
50.14. pg_conversion
50.15. pg_database
50.16. pg_db_role_setting
50.17. pg_default_acl
50.18. pg_depend
50.19. pg_description
50.20. pg_enum
50.21. pg_event_trigger
50.22. pg_extension
50.23. pg_foreign_data_wrapper
50.24. pg_foreign_server
50.25. pg_foreign_table
50.26. pg_index
50.27. pg_inherits
50.28. pg_init_privs
50.29. pg_language
50.30. pg_largeobject
50.31. pg_largeobject_metadata
50.32. pg_namespace
50.33. pg_opclass
50.34. pg_operator
50.35. pg_opfamily
50.36. pg_pltemplate
50.37. pg_policy
50.38. pg_proc
50.39. pg_range
50.40. pg_replication_origin
50.41. pg_rewrite
50.42. pg_seclabel
50.43. pg_shdepend
50.44. pg_shdescription
50.45. pg_shseclabel
50.46. pg_statistic
50.47. pg_tablespace
50.48. pg_transform
50.49. pg_trigger
50.50. pg_ts_config
50.51. pg_ts_config_map
50.52. pg_ts_dict
50.53. pg_ts_parser
50.54. pg_ts_template
50.55. pg_type
50.56. pg_user_mapping
50.57. System Views
50.58. pg_available_extensions
50.59. pg_available_extension_versions
50.60. pg_config
50.61. pg_cursors
50.62. pg_file_settings
50.63. pg_group
50.64. pg_indexes
50.65. pg_locks
50.66. pg_matviews
50.67. pg_policies
50.68. pg_prepared_statements
50.69. pg_prepared_xacts
50.70. pg_replication_origin_status
50.71. pg_replication_slots
50.72. pg_roles
50.73. pg_rules
50.74. pg_seclabels
50.75. pg_settings
50.76. pg_shadow
50.77. pg_stats
50.78. pg_tables
50.79. pg_timezone_abbrevs
50.80. pg_timezone_names
50.81. pg_user
50.82. pg_user_mappings
50.83. pg_views

系统目录是关系型数据库存放模式元数据的地方，比如表和列的信息，以及内部统计信息等。PostgreSQL的系统目录就是普通表。你可以删除并重建这些表、增加列、插入和更新数值，然后彻底把你的系统搞垮。通常情况下，我们不应该手工修改系统目录，通常有SQL命令可以做这些事情。（例如，CREATE DATABASE向 pg_database表插入一行 — 并且实际上在磁盘上创建该数据库。）。有几种特别深奥的操作例外，但是随着时间的流逝其中的很多也可以用 SQL 命令来完成，因此对系统目录直接修改的需求也越来越小。