内容

pg_description

一个存储数据库对象注释的系统表

pg_description 是一个存储数据库对象注释的系统目录表。

pg_description 添加于PostgreSQL 6.3。

目的

pg_description 存储由 COMMENT ON 命令定义的当前数据库中对象的任意用户定义描述。

有关全局对象（角色、表空间等）的注释，请参见 pg_shdescription。

按 PostgreSQL 版本定义

pg_description (PostgreSQL 17)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    | C         | not null | 
Indexes:
    "pg_description_o_c_o_index" PRIMARY KEY, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 16)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    | C         | not null | 
Indexes:
    "pg_description_o_c_o_index" PRIMARY KEY, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 15)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    | C         | not null | 
Indexes:
    "pg_description_o_c_o_index" PRIMARY KEY, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 14)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    | C         | not null | 
Indexes:
    "pg_description_o_c_o_index" PRIMARY KEY, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 13)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    | C         | not null | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 12)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    | C         | not null | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 11)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    |           | not null | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 10)

           Table "pg_catalog.pg_description"
   Column    |  Type   | Collation | Nullable | Default 
-------------+---------+-----------+----------+---------
 objoid      | oid     |           | not null | 
 classoid    | oid     |           | not null | 
 objsubid    | integer |           | not null | 
 description | text    |           | not null | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.6)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | not null
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.5)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | not null
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.4)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.3)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.2)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.1)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 9.0)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 8.4)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 8.3)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

pg_description (PostgreSQL 8.2)

 Table "pg_catalog.pg_description"
   Column    |  Type   | Modifiers 
-------------+---------+-----------
 objoid      | oid     | not null
 classoid    | oid     | not null
 objsubid    | integer | not null
 description | text    | 
Indexes:
    "pg_description_o_c_o_index" UNIQUE, btree (objoid, classoid, objsubid)

文档: pg_description

更改历史记录

示例

向表添加注释

postgres=# COMMENT ON TABLE foo IS 'Store all the things';
COMMENT

postgres=# SELECT * FROM pg_description WHERE objoid = 'foo'::REGCLASS;
 objoid | classoid | objsubid |     description      
--------+----------+----------+----------------------
  16470 |     1259 |        0 | Store all the things
(1 row)

从表中删除注释

postgres=# COMMENT ON TABLE foo IS NULL;
COMMENT

postgres=# SELECT * FROM pg_description WHERE objoid = 'foo'::REGCLASS;
 objoid | classoid | objsubid | description 
--------+----------+----------+-------------
(0 rows)

类别

DDL，系统目录

另请参阅

COMMENT ON，pg_shdescription，obj_description()

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