Re: Deferrable triggers

On Thu, 7 Nov 2003, Grant McLean wrote:

> On Fri, 2003-11-07 at 11:31, Stephan Szabo wrote:
> >
> > On Thu, 7 Nov 2003, Grant McLean wrote:
> >
> > > So it would seem that if I include the clauses:
> > >
> > >         on delete restrict on update restrict
> > >
> > > Then the 'deferrable' which follows is only applied to creates and
> > > not to updates or deletes.
> > >
> > > Since 'restrict' is the default, the clauses aren't adding any value
> > > and can be omitted.  In my case, the SQL is generated for me by
> > > PowerDesigner.  My workaround is to tweak the PowerDesigner output
> > > definition to not include this line.
> > >
> > > I have seen this behaviour in both 7.2 and 7.3.  Is it a bug?  Or
> > > am I misunderstanding something?
> >
> > Restrict is not the default, there is a difference between restrict and no
> > action. In fact I believe the main point of restrict (which IIRC was added
> > for sql99) is to allow you to have a deferred constraint that can do
> > immediate checking of validity on pk changes.
>
> I was basing my reasoning on the CREATE TABLE documentation which says:
>
>   NO ACTION
>
>     Produce an error indicating that the deletion or update would create
>     a foreign key constraint violation. This is the default action.
>
>   RESTRICT
>
>     Same as NO ACTION.
>
> So as you pointed out, RESTRICT is not the default, but according to the
> docs NO ACTION is the default and RESTRICT is the same as NO ACTION.
> Is the difference between the two documented anywhere?

Hmm, I don't think so actually.  I'm surprised that we hadn't had that
mistake pointed out before. The restrict entry should mention the
fact that it's non-deferring.

To -hackers: Is it still safe to send small documentation patches for 7.4
at this point?