Re: join pushdown and issue with foreign update

On Wed, Jun 2, 2021 at 6:32 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I wrote:
> > I think a preferable fix involves making sure that the correct
> > record-type typmod is propagated to record_in in this context.
> > Alternatively, maybe we could insert the foreign table's rowtype
> > during execution of the input operation, without touching the
> > plan as such.
>
> Here's a draft-quality patch based on that idea.

This looks good to me.  Yeah, I agree that reversing our decision to
mark row-id wholerow Vars in as RECORD rather than a specific reltype
will have to wait until we hear more complaints than just this one,
which seems fixable with a patch like this.

> It resolves
> the offered test case, but I haven't beat on it beyond that.

Given that we don't (no longer) support pushing down the join of child
target relations with other relations, I don't think we have other
cases that are affected at this point.  I have a feeling that your
patch will have fixed things enough that the same problem will not
occur when we have join pushdown under UPDATE occurring in more cases.

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