BUG #2138: Feature request: handle foreign key constraints on arrays

On 1/2/06, Bernhard Rosenkraenzer <bero@arklinux.org> wrote:

The following bug has been logged online:

Bug reference: 2138
Logged by: Bernhard Rosenkraenzer
Email address: bero@arklinux.org
PostgreSQL version: 8.1.1
Operating system: Linux (Ark Linux 2005.2)
Description: Feature request: handle foreign key constraints on
arrays
Details:

Best illustrated by an example:

an example of what *NOT* to do?

A company has several offices and some employees who work in office #1 some
of the time, and in office #2 at a different time.

It would be nice to represent them in the database like this:
CREATE TABLE offices(id SERIAL8 UNIQUE PRIMARY KEY, street VARCHAR(128));

UNIQUE and PRIMARY KEY are the same...

CREATE TABLE employees(id SERIAL8 UNIQUE PRIMARY KEY, name VARCHAR(128),
workplace BIGINT[] REFERENCES offices(id) ON UPDATE CASCADE);

what you should do is:

CREATE TABLE offices(id SERIAL8 PRIMARY KEY, street VARCHAR(128));

CREATE TABLE employees(id SERIAL8 UNIQUE PRIMARY KEY, name VARCHAR(128));

CREATE TABLE emp_offices (employee bigint not null references employees,
office bigint not null
references offices,
PRIMARY KEY(employee, office));

Currently postgres refuses to do this because BIGINT[] and BIGINT are
different types, it would be nice to simply apply the constraint to all
entries in the array if a constraint for type X is applied to X[].

--
Atentamente,
Jaime Casanova
(DBA: DataBase Aniquilator ;)