Re: special integrity constraints

On Mon, 22 Mar 2004, Erik Thiele wrote:

> On Mon, 22 Mar 2004 12:13:29 +0200 (EET)
> Achilleus Mantzios <achill(at)matrix(dot)gatewaynet(dot)com> wrote:
>
> > O kyrios Erik Thiele egrapse stis Mar 22, 2004 :
> >
> > Did you check out the DEFERRABLE option on the constraint?
> >
>
> DEFERRABLE
> NOT DEFERRABLE
>
> This controls whether the constraint can be deferred. A constraint that
> is not deferrable will be checked immediately after every command.
> Checking of constraints that are deferrable may be postponed until the
> end of the transaction (using the SET CONSTRAINTS command). NOT
> DEFERRABLE is the default.
>
> !!!! Only foreign key constraints currently accept
> this clause. All other constraint types are not deferrable. !!!!
>
> my constraint is not a foreign key constraint....

However, foreign keys are implemented using "constraint triggers". They're
really not documented much (because they're a not really separately
supported implementation detail), but you can theoretically make
triggers that are deferred to immediately before commit time.