目录

pg_shdescription

记录共享数据库对象注释的系统表

pg_shdescription 是一个 系统目录 表，用于记录共享数据库对象的注释。

pg_shdescription 添加于 PostgreSQL 8.2。

该表在集群的所有数据库之间共享。

按 PostgreSQL 版本定义

pg_shdescription (PostgreSQL 19)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" PRIMARY KEY, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 18)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" PRIMARY KEY, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 17)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" PRIMARY KEY, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 16)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" PRIMARY KEY, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 15)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" PRIMARY KEY, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 14)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" PRIMARY KEY, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 13)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 12)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text | C         | not null | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 11)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text |           | not null | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 10)

         Table "pg_catalog.pg_shdescription"
   Column    | Type | Collation | Nullable | Default 
-------------+------+-----------+----------+---------
 objoid      | oid  |           | not null | 
 classoid    | oid  |           | not null | 
 description | text |           | not null | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.6)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | not null
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.5)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | not null
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.4)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.3)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.2)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.1)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 9.0)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 8.4)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 8.3)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

pg_shdescription (PostgreSQL 8.2)

Table "pg_catalog.pg_shdescription"
   Column    | Type | Modifiers 
-------------+------+-----------
 objoid      | oid  | not null
 classoid    | oid  | not null
 description | text | 
Indexes:
    "pg_shdescription_o_c_index" UNIQUE, btree (objoid, classoid), tablespace "pg_global"
Tablespace: "pg_global"

文档: pg_shdescription

变更历史

示例

为 表空间添加注释

postgres=# COMMENT ON TABLESPACE tblspc_1 IS 'Store some of the things';
COMMENT

postgres=# SELECT * FROM pg_shdescription WHERE objoid = 
          (SELECT oid FROM pg_tablespace WHERE spcname = 'tblspc_1');
 objoid | classoid |       description        
--------+----------+--------------------------
  16385 |     1213 | Store some of the things
(1 row)

也可以使用函数 shobj_description() 来检索表空间注释。

postgres=# SELECT shobj_description(
                 (SELECT oid FROM pg_tablespace WHERE spcname = 'tblspc_1'),
                 'pg_tablespace'); 
    shobj_description     
--------------------------
 Store some of the things
(1 row)

从 表空间移除注释

postgres=# COMMENT ON TABLESPACE space_1 IS NULL;
COMMENT

postgres=# SELECT * FROM pg_shdescription WHERE objoid = 
          (SELECT oid FROM pg_tablespace WHERE spcname = 'tblspc_1');
 objoid | classoid | description 
--------+----------+-------------
(0 rows)

分类

集群范围表, DDL, 系统目录

另请参阅

pg_description, pg_shdepend, COMMENT ON, shobj_description()

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