Re: Table constraints

On Thu, 28 Mar 2002, Oleg Lebedev wrote:

> Hi everybody,
> I saw a couple of messages regarding rule/constraint/trigger standards
> which Tom proposed to adopt in postgres. I've read through the current
> specs, but still can't figure it out. I am using version 7.1.3 and this
> is what I am trying to do:
> I have 2 tables:
> Set { type_id int,
>         set_desc varchar(128) }
> Type { id int primary key }
>
> I want to update a row in Type table and cascade this update to update
> Set table. I declare a constraint as follows:
> ALTER TABLE Set
> ADD CONSTRAINT fk_type
> FOREIGN KEY (type_id)
> REFERENCES Type (id)
> ON UPDATE CASCADE;
> Postgres gives me a NOTICE and creates the constraint.
>
> Here are some questions:
> Why pg_relcheck table is still empty after the constraint is added?

relcheck is only for CHECK constraints.

> Why instead it created 5 triggers (I checked pg_class.reltriggers for
> Set table): 3 called "fk_type" on Set and 2 unnamed on Type?

Hmm, it should have only created 3 triggers, 1 on set and 2 on Type
and they should have all had tgconstrname set to fk_type.
What does select * from pg_trigger say?

> Why when I try to update id in Type table I get RI violation error?
> Shouldn't it cascade the update?

It works for me in 7.2.  I don't have 7.1.3 to test against right now
but I'm pretty sure that's in the regression test.

Can you give a short script that illustrates the problem?