Re: Odd system-column handling in postgres_fdw join pushdown patch

Robert Haas <robertmhaas@gmail.com> writes:
> 2. When a join is pushed down, deparse system columns using something
> like "CASE WHEN r1.* IS NOT NULL THEN 0 END", except for the table OID
> column, which gets deparsed with the table OID in place of 0.  This
> delivers the correct behavior in the presence of outer joins.

Um, why would that be necessary?  Surely the correct things will happen
on the far end without that, if it's implementing the same join semantics
as the local query would have.
        regards, tom lane