Re: Tables cannot have INSTEAD OF triggers

On 2015-04-02 16:42:43 -0400, Peter Eisentraut wrote:
> On 4/2/15 11:50 AM, Dean Rasheed wrote:
> > Well actually the fact that the code is structured that way is
> > somewhat academic. INSTEAD OF triggers on views don't support WHEN
> > conditions -- deliberately so, since it would be difficult to know in
> > general what to do if the trigger didn't fire. So ExecInsert is
> > implicitly using the existence of the trigger to imply that it will
> > fire, although arguably it would be neater for it to double-check
> > that, and error out if for some reason the trigger didn't fire. In any
> > case, that doesn't establish any kind of behavioural precedent for how
> > a conditional INSTEAD OF trigger on a table ought to work.
> 
> I think the upshot is that INSTEAD OF triggers work in a particular way
> because that's what is needed to support updatable views.  If triggers
> on tables should behave differently, maybe it should be a separate
> trigger type.  Maybe it would be feasible to extend BEFORE triggers to
> support RETURNING, for example?

What in the above prohibits extending the behaviour to tables? I have
yet to see what compatibility or similarity problem that'd pose. It
seems all mightily handwavy to me.

Greetings,

Andres Freund