pg_cast

一个存储数据类型转换路径的系统表

pg_cast 是一个系统目录表，它存储了内置和用户定义的数据类型转换路径。

pg_cast 在 PostgreSQL 7.3 中添加。

psql

\dC 命令可以列出可用的转换。

按 PostgreSQL 版本定义

pg_cast (PostgreSQL 19)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" PRIMARY KEY, btree (oid)
    "pg_cast_source_target_index" UNIQUE CONSTRAINT, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 18)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" PRIMARY KEY, btree (oid)
    "pg_cast_source_target_index" UNIQUE CONSTRAINT, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 17)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" PRIMARY KEY, btree (oid)
    "pg_cast_source_target_index" UNIQUE CONSTRAINT, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 16)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" PRIMARY KEY, btree (oid)
    "pg_cast_source_target_index" UNIQUE CONSTRAINT, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 15)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" PRIMARY KEY, btree (oid)
    "pg_cast_source_target_index" UNIQUE CONSTRAINT, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 14)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" PRIMARY KEY, btree (oid)
    "pg_cast_source_target_index" UNIQUE CONSTRAINT, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 13)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 12)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 oid         | oid    |           | not null | 
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 11)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 10)

              Table "pg_catalog.pg_cast"
   Column    |  Type  | Collation | Nullable | Default 
-------------+--------+-----------+----------+---------
 castsource  | oid    |           | not null | 
 casttarget  | oid    |           | not null | 
 castfunc    | oid    |           | not null | 
 castcontext | "char" |           | not null | 
 castmethod  | "char" |           | not null | 
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.6)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.5)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.4)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.3)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.2)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.1)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 9.0)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 8.4)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
 castmethod  | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 8.3)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

pg_cast (PostgreSQL 8.2)

    Table "pg_catalog.pg_cast"
   Column    |  Type  | Modifiers 
-------------+--------+-----------
 castsource  | oid    | not null
 casttarget  | oid    | not null
 castfunc    | oid    | not null
 castcontext | "char" | not null
Indexes:
    "pg_cast_oid_index" UNIQUE, btree (oid)
    "pg_cast_source_target_index" UNIQUE, btree (castsource, casttarget)

文档: pg_cast

变更历史

PostgreSQL 8.4
- 添加了列 castmethod (提交 092bc496)
PostgreSQL 7.3
- 已添加（提交 97377048）

示例

列出所有 xml 转换

postgres=# SELECT castsource::regtype, casttarget::regtype, castfunc::regproc,
                  castcontext, castmethod
             FROM pg_catalog.pg_cast
             WHERE castsource = 'xml'::regtype OR casttarget = 'xml'::regtype
          ORDER BY castsource::regtype::TEXT;

    castsource     |    casttarget     | castfunc | castcontext | castmethod 
-------------------+-------------------+----------+-------------+------------
 character         | xml               | xml      | e           | f
 character varying | xml               | xml      | e           | f
 text              | xml               | xml      | e           | f
 xml               | text              | -        | a           | b
 xml               | character varying | -        | a           | b
 xml               | character         | -        | a           | b
(6 rows)

postgres=# \dC xml
                               List of casts
    Source type    |    Target type    |      Function      |   Implicit?   
-------------------+-------------------+--------------------+---------------
 character         | xml               | xml                | no
 character varying | xml               | xml                | no
 text              | xml               | xml                | no
 xml               | character         | (binary coercible) | in assignment
 xml               | character varying | (binary coercible) | in assignment
 xml               | text              | (binary coercible) | in assignment
(6 rows)

参考资料

PostgreSQL 文档: pg_cast

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版本图表

实用概述

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目录

pg_cast

psql

按 PostgreSQL 版本定义

pg_cast (PostgreSQL 19)

pg_cast (PostgreSQL 18)

pg_cast (PostgreSQL 17)

pg_cast (PostgreSQL 16)

pg_cast (PostgreSQL 15)

pg_cast (PostgreSQL 14)

pg_cast (PostgreSQL 13)

pg_cast (PostgreSQL 12)

pg_cast (PostgreSQL 11)

pg_cast (PostgreSQL 10)

pg_cast (PostgreSQL 9.6)

pg_cast (PostgreSQL 9.5)

pg_cast (PostgreSQL 9.4)

pg_cast (PostgreSQL 9.3)

pg_cast (PostgreSQL 9.2)

pg_cast (PostgreSQL 9.1)

pg_cast (PostgreSQL 9.0)

pg_cast (PostgreSQL 8.4)

pg_cast (PostgreSQL 8.3)

pg_cast (PostgreSQL 8.2)

变更历史

示例

参考资料

分类

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