Re: Oddity in EXPLAIN for foreign/custom join pushdown plans

> On 2016/08/01 22:25, Kouhei Kaigai wrote:
>
> I wrote:
> >>> a broader
> >>> word like "Processing" seems to work well because we allow various
> >>> kinds of operations to the remote side, in addition to scans/joins,
> >>> to be performed in that one Foreign Scan node indicated by "Foreign
> >>> Processing", such as aggregation, window functions, distinct, order
> >>> by, row locking, table modification, or combinations of them.
>
> >> On 2016/07/29 13:28, Ashutosh Bapat wrote:
> >>> "Scan" is a better word than "Processing". From plan's perspective it's
> >>> ultimately a Scan (on the data produced by the foreign server) and not
> >>> processing.
>
> I wrote:
> >> Exactly, but one thing I'm concerned about is the table modification
> >> case; the EXPLAIN output would be something like this:
> >>
> >> Foreign Scan
> >> Remote SQL: INSERT INTO remote_table VALUES ...
> >>
> >> That would be strange, so I think a more broader word is better. I
> >> don't think "Foreign Processing" is best. "Foreign Upper" might be much
> >> better because the corresponding path is created by calling
> >> GetForeignUpperPaths.
>
> > Be "Foreign %s", and gives "Insert" label by postgres_fdw; which knows
> > the ForeignScan node actually insert tuples.
> > From the standpoint of users, it looks "Foreign Insert".
>
> My concern here is EXPLAIN for foreign joins. I think it's another
> problem how we handle Foreign Scan plan nodes representing
> post-scan/join operations in EXPLAIN, so I'd like to leave that for
> another patch.
>
What is the post-scan/join operations? Are you saying EPQ recheck and
alternative local join plan?

Thanks,
--
NEC Business Creation Division / PG-Strom Project
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>