Re: Join push-down support for foreign tables

Kaigai-san,

Oops. I rebased the patch onto your v4 custom/foreign join patch.
But as you mentioned off-list, I found a flaw about inappropriate
change about NestPath still remains in the patch... I might have made
my dev branch into unexpected state. I'll check it soon.

2015-02-16 13:13 GMT+09:00 Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>:
> Hanada-san,
>
> Your patch mixtures enhancement of custom-/foreign-scan interface and
> enhancement of contrib/postgres_fdw... Probably, it is a careless mis-
> operation.
> Please make your patch as differences from my infrastructure portion.
>
>
> Also, I noticed this "Join pushdown support for foreign tables" patch
> is unintentionally rejected in the last commit fest.
> https://commitfest.postgresql.org/3/20/
> I couldn't register myself as reviewer. How do I operate it on the
> new commitfest application?
>
> Thanks,
> --
> NEC OSS Promotion Center / PG-Strom Project
> KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>
>
>
>> -----Original Message-----
>> From: pgsql-hackers-owner(at)postgresql(dot)org
>> [mailto:pgsql-hackers-owner(at)postgresql(dot)org] On Behalf Of Shigeru Hanada
>> Sent: Monday, February 16, 2015 1:03 PM
>> To: Robert Haas
>> Cc: PostgreSQL-development
>> Subject: Re: [HACKERS] Join push-down support for foreign tables
>>
>> Hi
>>
>> I've revised the patch based on Kaigai-san's custom/foreign join patch
>> posted in the thread below.
>>
>> http://www.postgresql.org/message-id/9A28C8860F777E439AA12E8AEA7694F80
>> 108C355(at)BPXM15GP(dot)gisp(dot)nec(dot)co(dot)jp
>>
>> Basically not changed from the version in the last CF, but as Robert
>> commented before, N-way (not only 2-way) joins should be supported in the
>> first version by construct SELECT SQL by containing source query in FROM
>> clause as inline views (a.k.a. from clause subquery).
>>
>> 2014-12-26 13:48 GMT+09:00 Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>:
>> > 2014-12-16 1:22 GMT+09:00 Robert Haas <robertmhaas(at)gmail(dot)com>:
>> >> On Mon, Dec 15, 2014 at 3:40 AM, Shigeru Hanada
>> >> <shigeru(dot)hanada(at)gmail(dot)com> wrote:
>> >>> I'm working on $SUBJECT and would like to get comments about the
>> >>> design. Attached patch is for the design below.
>> >>
>> >> I'm glad you are working on this.
>> >>
>> >>> 1. Join source relations
>> >>> As described above, postgres_fdw (and most of SQL-based FDWs) needs
>> >>> to check that 1) all foreign tables in the join belong to a server,
>> >>> and
>> >>> 2) all foreign tables have same checkAsUser.
>> >>> In addition to that, I add extra limitation that both inner/outer
>> >>> should be plain foreign tables, not a result of foreign join. This
>> >>> limiation makes SQL generator simple. Fundamentally it's possible
>> >>> to join even join relations, so N-way join is listed as enhancement
>> >>> item below.
>> >>
>> >> It seems pretty important to me that we have a way to push the entire
>> >> join nest down. Being able to push down a 2-way join but not more
>> >> seems like quite a severe limitation.
>> >
>> > Hmm, I agree to support N-way join is very useful. Postgres-XC's SQL
>> > generator seems to give us a hint for such case, I'll check it out
>> > again.
>> >
>> > --
>> > Shigeru HANADA
>>
>>
>>
>> --
>> Shigeru HANADA

--
Shigeru HANADA