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

On Tue, Apr 05, 2016 at 03:41:00PM +0900, Etsuro Fujita wrote:
> On 2016/03/29 15:37, Etsuro Fujita wrote:
> >I added two helper functions: GetFdwScanTupleExtraData and
> >FillFdwScanTupleSysAttrs. The FDW author could use the former to get
> >info about system attributes other than ctids and oids in fdw_scan_tlist
> >during BeginForeignScan, and the latter to set values for these system
> >attributes during IterateForeignScan (InvalidTransactionId for
> >xmins/xmaxs, InvalidCommandId for cmins/cmaxs, and valid values for
> >tableoids). Attached is a proposed patch for that. I also slightly
> >simplified the changes to make_tuple_from_result_row and
> >conversion_error_callback made by the postgres_fdw join pushdown patch.
> > What do you think about that?
>
> I revised comments a little bit. Attached is an updated version of the
> patch. I think this issue should be fixed in advance of the PostgreSQL
> 9.6beta1 release.

Of the foreign table columns affected here, I bet only tableoid sees
non-negligible use. Even tableoid is not very prominent, so I would not have
thought of this as a beta1 blocker. What about this bug makes pre-beta1
resolution especially valuable?