PostgreSQL外键不存在，继承问题？

Question

我在数据库中遇到外键问题，可能与继承有关？
下面是基本设置：

-- table address
CREATE TABLE address
(
  pk_address serial NOT NULL,
  fk_gadmid_0 integer NOT NULL, -- this table already exists, no problem here
  street character varying(100),
  zip character varying(10),
  city character varying(50),
  public boolean,
  CONSTRAINT address_primarykey PRIMARY KEY (pk_address),
  CONSTRAINT gadmid_0_primarykey FOREIGN KEY (fk_gadmid_0)
      REFERENCES adm0 (gadmid_0) MATCH SIMPLE
      ON UPDATE CASCADE ON DELETE NO ACTION
)
WITH (
  OIDS=FALSE
);
ALTER TABLE address OWNER TO postgres;  

-- table stakeholder (parent)
CREATE TABLE stakeholder
(
    pk_stakeholder integer DEFAULT nextval('common_stakeholder_seq') NOT NULL,
    fk_stakeholder_type integer NOT NULL, -- this table also exists, no problem here
    name character varying(255) NOT NULL,
    CONSTRAINT stakeholder_primarykey PRIMARY KEY (pk_stakeholder),
    CONSTRAINT stakeholder_fk_stakeholder_type FOREIGN KEY (fk_stakeholder_type)
        REFERENCES stakeholder_type (pk_stakeholder_type) MATCH SIMPLE
        ON UPDATE CASCADE ON DELETE NO ACTION
)
WITH (
    OIDS=FALSE
);
ALTER TABLE stakeholder OWNER TO postgres;  

-- table individual (child of stakeholder)
CREATE TABLE individual
(
    firstname character varying(50),
    fk_title integer, -- this table also exists, no problem here
    email1 character varying (100),
    email2 character varying (100),
    phone1 character varying (50),
    phone2 character varying (50),
    CONSTRAINT individual_primarykey PRIMARY KEY (pk_stakeholder),
    CONSTRAINT title_foreignkey FOREIGN KEY (fk_title)
        REFERENCES title (pk_title) MATCH SIMPLE
        ON UPDATE CASCADE ON DELETE CASCADE
) INHERITS (stakeholder)
WITH (
    OIDS=FALSE
);
ALTER TABLE individual OWNER TO postgres;  

-- link between stakeholder and address
CREATE TABLE l_stakeholder_address
(
    pk_l_stakeholder_address serial NOT NULL,
    fk_stakeholder integer NOT NULL REFERENCES stakeholder,
    fk_address integer NOT NULL REFERENCES address,
    CONSTRAINT l_stakeholder_address_primarykey PRIMARY KEY (pk_l_stakeholder_address),
    CONSTRAINT l_stakeholder_address_fk_stakeholder FOREIGN KEY (fk_stakeholder)
        REFERENCES stakeholder (pk_stakeholder) MATCH SIMPLE
        ON UPDATE CASCADE ON DELETE NO ACTION,
    CONSTRAINT l_stakeholder_address_fk_address FOREIGN KEY (fk_address)
        REFERENCES address (pk_address) MATCH SIMPLE
        ON UPDATE CASCADE ON DELETE NO ACTION
)
WITH (
    OIDS=FALSE
);
ALTER TABLE l_stakeholder_address OWNER TO postgres;

到目前为止，没问题。然后我尝试添加一些值：

INSERT INTO individual (pk_stakeholder, fk_stakeholder_type, name, firstname, fk_title, email1, email2, phone1, phone2) 
  VALUES (1, 8, 'Lastname', 'Firstname', 1, 'me@you.com', '', '', '');
INSERT INTO address (pk_address, fk_gadmid_0, street, zip, city, public)  
  VALUES (1, 126, 'Address', '', 'City', FALSE);
INSERT INTO l_stakeholder_address (pk_l_stakeholder_address, fk_stakeholder, fk_address)  
  VALUES (DEFAULT, 1, 1);

最后我遇到了一个错误（SQL 状态 23503），说密钥 (fk_stakeholder)=(1) 在表“利益相关者”中不存在。
前 2 个插入很好，我可以在数据库中看到它们：

stakeholder:
pk_stakeholder | ...
----------------------
1              | ...

address:
pk_address | ...
--------------------
1          | ...

我做错了什么？我必须承认我对 PostgreSQL（使用 8.4）相当陌生，但我什至不确定这是否是 PG 的问题，也许我只是缺乏一些基本的数据库设计理解......
无论哪种方式，到目前为止，我已经尝试了几乎所有我能想到的方法，我还尝试像 PostgreSQL : Transaction and foreign key problem 那样使 FK 可延迟，但不知何故，这也不起作用。

Answer 1

您的分析完全正确：这是因为继承。检查外键时，不考虑子表。

一般来说，继承和外键在 PostgreSQL 中不能很好地混合。一个主要问题是您不能跨表设置唯一约束。

Reference

Answer 2

您可以使用附加表 individual_pks (individual_pk integer primary key) 来解决它，其中包含来自父项和子项的所有主键，这将使用触发器进行维护（非常简单 - 插入时插入 individual_pks，删除时从中删除，更新它更新时，如果它改变了individual_pk)。

然后你将外键指向这个额外的表而不是一个子表。会有一些小的性能影响，但仅限于添加/删除行时。

或者忘记继承并使用旧方法 - 只需一个包含一些可为空列的表。