Re: Troubleshooting SPI_execp() failed in RI_FKey_cascade_del()

On Wed, 12 Jun 2002, Joshua b. Jore wrote:

> The following sql demonstrates the problem. What I'm getting at here is
> cases where the rows in "b" are being altered instead of being deleted
> consequently the delete to "a" shouldn't happen.
>
> create table a (id int4 primary key);
> create table b (id int4 references a on delete cascade);
> create rule b0 as on delete to b do instead nothing;
>
> insert into a values (1);
> insert into b values (1);
> delete from a;

When you do the delete from a, the constraint will no longer
be satisifed. It throws the error to prevent the delete
from working. Maybe throwing a standard constraint violation
would be enough, but I'd worry that there'd be some other
return case that we should know about.

In general on <x> rules with on <x> action foreign key constraints
are a bad idea. I'd almost want to disallow the above entirely.