[Dovecot] Quota PostgreSQL INSERT trigger

[Timo Sirainen]

On Thu, 2011-12-15 at 09:37 +0100, Adis Nezirovic wrote:
> Wiki instructions for creating insert trigger for PostgreSQL are wrong
>   http://wiki.dovecot.org/Quota/Dict
> 
> Calling INSERT on the table from within BEFORE INSERT trigger creates
> cascading trigger.

Yes..

> Instead, one should return NEW record from the trigger, and it will be
> inserted after trigger execution.

But does this handle race conditions when a record is inserted/deleted
while the trigger is being run? That's the reason this trigger is so
complex.

>     BEGIN
>       IF NEW.messages = 0 THEN
>         RETURN NEW;
>       ELSE
>         NEW.messages = - NEW.messages;
>         RETURN NEW;
>       END IF;
>     EXCEPTION WHEN unique_violation THEN
>       -- someone just inserted the record, update it
>     END;

I'd guess the unique_violation is never caught here, and instead the
whole INSERT fails?