Postgres：外表的外键 [英] Postgres: foreign key to foreign table

问题描述

我有一张外国桌子，例如：

I have a foreign table, for example:

CREATE FOREIGN TABLE film (
    id          varchar(40) NOT NULL,
    title       varchar(40) NOT NULL,
    did         integer NOT NULL,
    date_prod   date,
    kind        varchar(10),
    len         interval hour to minute
)
SERVER film_server;

，其中id为该表的主键（在远程数据库中设置）。我想让一个本地表引用该外表，并在该本地表上设置外键约束-例如：

with id as the primary key for that table (set in the remote database). I would like to have a local table reference the foreign table, and set a foreign key constraint on the local table -- for example:

CREATE TABLE actor (
    id          varchar(40) NOT NULL,
    name       varchar(40) NOT NULL,
    film_id       varchar(40) NOT NULL,
)

ALTER TABLE actor ADD CONSTRAINT actor_film_fkey FOREIGN KEY (film_id) 
    REFERENCES film(id);

但是，当我尝试添加外键约束时，出现错误：

However, when I try to add the foreign key constraint, I get the error:

ERROR:  referenced relation "film" is not a table

是否可以向外表添加外键约束？

Is it possible to add a foreign key constraint to a foreign table?

推荐答案

无法在外部表上创建索引。

It's no possible create index on foreign tables.

创建索引idx_film ON电影（id）;

CREATE INDEX idx_film ON film (id);

这是错误：

错误：无法在外部表上创建索引

ERROR: cannot create index on foreign table

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