How to add Foreign key constraint on array in PostgreSQL?

Question

How to add Foreign key constraint on array in PostgreSQL?

look_up table for roles

CREATE TABLE party_role_cd
(
  party_role_cd bigint NOT NULL,
  code character varying(80) NOT NULL,
  CONSTRAINT party_role_cd PRIMARY KEY (party_role_cd)
);

Party can have zero or many roles [ 0-N relationship ]

CREATE TABLE party
(
  party_id biging NOT NULL,
  party_role_cd bigint[] NOT NULL,
  CONSTRAINT party_id PRIMARY KEY (party_id)
);

How to add the foreign key constraint for party_role_cd array in party table?

Answer 1

That's not implemented in PostgreSQL. Currently, FK constraints only operate on equality between whole column values. No array-to-element references. There is an open TODO item that has been added in 2010. See:

• https://wiki.postgresql.org/wiki/Todo#Referential_Integrity
• https://www.postgresql.org/message-id/1288033876.6278.6.camel@vanquo.pezone.net

There were even attempts to implement it, but never to completion.