Re: Tables cannot have INSTEAD OF triggers

On 2015-04-01 12:46:05 -0400, Robert Haas wrote:
> On Wed, Apr 1, 2015 at 12:04 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> > On 2015-04-01 11:40:13 -0400, Robert Haas wrote:
> > Without INSTEAD OF you can't, to my knowledge, return a valid tuple from
> > the top level table without also inserting into it. Returning NULL after
> > redirecting the tuple into a child table will break RETURNING; not
> > returning NULL will insert the tuple in the top level table.
> >
> > So the only way to do redirection that doesn't break RETURNING without
> > rules is to insert the tuple in the child in the BEFORE trigger return
> > NEW and delete the top level table row in an AFTER trigger. That sucks.
>
> So, the idea is that INSTEAD OF would behave like BEFORE but the tuple
> it returns wouldn't actually be inserted? That wasn't clear to me
> from the OP, but I guess it would be a reasonable way to go.

I'm not sure what the OP intended, but to me that's pretty much the only
reasonable definition of INSTEAD OF for tables that I can think of.

Greetings,

Andres Freund