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

On 2016/04/14 13:04, Robert Haas wrote:
> On Wed, Apr 13, 2016 at 11:21 PM, Etsuro Fujita
> <fujita.etsuro@lab.ntt.co.jp> wrote:
>>>> 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.
>>> I think that that would cause useless data transfer for such culumns.
>>> Why not set values locally for such columns?

> Because that doesn't work properly when there are outer joins
> involved.

Understood.  It looks like I overlooked Ashutosh's mail about that. 
Thanks, Robert and Ashutosh!

Best regards,
Etsuro Fujita