Re: What Is The Firing Order?

Added to TODO:

    * Allow user to control trigger firing order

> On Fri, 7 Sep 2001, Bruce Momjian wrote:
>
> > > > I think that'd probably work, although I think that you probably
> > > > want to ensure that deferred constraint triggers run after normal
> > > > triggers and immediate constraints when you're running statements
> > > > in their own implicit transactions, since that would model the
> > > > behavior (check on commit) better.
> > >
> > > Yes, the semantics of immediate and deferred triggers wouldn't change.
> > > I'm just suggesting that when the system has a choice of legal firing
> > > orders, it adopt an "alphabetical order" rule.  AFAICS, all it would
> > > take to implement this is for RelationBuildTriggers to sort the list
> > > of triggers just after it's read them from pg_trigger and before it
> > > inserts them into the TriggerDesc structure (ie, about line 638 of
> > > trigger.c in current sources).  The latter insertion is where they
> > > are divided into categories, so the sorting would end up only affecting
> > > the ordering within categories.
> > >
> > > The interesting question is not that, really, but whether an
> > > alphabetical-ordering rule will be useful and convenient.  I don't
> > > recall exactly how the system chooses names for triggers that it creates
> > > --- if the user can't control those at all then this idea may not be
> > > helpful.
> >
> > Should we get a system where the user can control the firing, perhaps
> > using oid order?
>
> I don't think oid order would help, because what happens if you've say got
> a trigger and then want to add another before it?  I'd guess the most
> general way would be to give triggers some kind of numeric ordering not
> associated with anything else, but then you need ways to set it on create
> trigger and probably an alter trigger way to change it. :(  I'd guess that
> there'd be a default value if you didn't set it, and that triggers of the
> same value would run in indeterminate order like before.
>
>
>
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