Re: BUG #16644: null value for defaults in OLD variable for trigger

On Mon, Oct 26, 2020 at 12:19 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Amit Langote <amitlangote09@gmail.com> writes:
> > On Mon, Oct 26, 2020 at 5:53 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> Moreover, it's more correct, even disregarding the problem
> >> at hand, because the tlist isn't a perfectly accurate depiction of
> >> the relation rowtype: ExecCleanTypeFromTL will not derive the correct
> >> info for dropped columns.
>
> > Hmm, I don't understand.  Isn't it the planner's job to make the
> > targetlist correctly account for dropped columns; what
> > expand_targetlist() does?
>
> Yes, there are columns in the tlist to match them, but ExecCleanTypeFromTL
> cannot mark those columns as "attisdropped".

Ah, okay.

> The column data type
> likely won't be right either.  The latter shouldn't matter, if the
> column is being filled with a null ... but I'm a bit surprised that
> we've gotten away this long with not being honest about attisdropped.

Yeah, I guess most places downstream of ExecModifyTable() seem to rely
on getting that information indirectly via the isnull flag of the
tuple itself.

--
Amit Langote
EDB: http://www.enterprisedb.com