Re: table inheritance and foreign key troubles

(hopefully this doesn't double post... stupid mail system)

On Tue, 11 Sep 2001, Christof Glaser wrote:

> On Tuesday, 11. September 2001 10:04, Kevin Way wrote:
> > I'm having a little trouble with some inherited tables and a foreign
> > key.  Here's a simplified case, to show the trouble.
> >
> > CREATE TABLE node (
> >     node_id     SERIAL NOT NULL,
> >     name        TEXT NOT NULL,
> >     PRIMARY KEY (node_id)
> > );
> > -- works just fine
> >
> > CREATE TABLE users (
> >     email       TEXT NOT NULL
> > ) INHERITS (node);
> > -- so far so good....
> >
> > CREATE TABLE item (
> >     reason      TEXT NOT NULL,
> >     author_id   INT NOT NULL REFERENCES users (node_id)
> > ) INHERITS (node);
> > ERROR:  UNIQUE constraint matching given keys for referenced table
> > "users" not found
> 
> That means, there is no UNIQUE constraing on users.node_id ;-)
> Since users inherits that field from node, just make node.node_id 
> unique, or even a primary key.

Actually node.node_id looks to be a pkey, but primary keys/unique don't
inherit, so users.node_id doesn't have the constraint.  You'll need
a primary key(node_id) on users as well (note that this won't actually
enforce that values are unique across both node and users just within
each table. See past discussions about inheritance and foreign keys...