Re: The plan for FDW-based sharding

> On Wed, Mar 2, 2016 at 6:54 PM, Alexander Korotkov
> <a(dot)korotkov(at)postgrespro(dot)ru> wrote:
>> If FDWs existed then Postgres XC/XL were being developed then I believe they
>> would try to build full-featured prototype of FDW based sharding. If this
>> prototype succeed then we could make a full roadmap.
>
> Speaking here with my XC hat, that's actually the case. A couple of
> years back when I worked on it, there were discussions about reusing
> FDW routines for the purpose of XC, which would have been roughly
> reusing postgres_fdw + the possibility to send XID, snapshot and
> transaction timestamp to the remote nodes after getting that from the
> GTM (global transaction manager ensuring global data visibility and
> consistency), and have the logic for query pushdown in the FDW itself
> when planning query on what would have been roughly foreign tables
> (not entering in the details here, those would have not been entirely
> foreign tables). At this point the global picture was not completely
> set, XC being based on 9.1~9.2 and the FDW base routines were not as
> extended as they are now. As history has told, this global picture has
> never showed up, though it would should XC have been merged with 9.3.
> The point is that XC would have moved as using the FDW approach, as a
> set of plugins.
>
> This was a reason behind this email of 2013 on -hackers actually:
> http://www.postgresql.org/message-id/CAB7nPqTDjf-58wuf-xZ01NKJ7WF0E+EUKgGQHd0igVsOD4hCJQ@mail.gmail.com
>
> There were as well discussions about making the connection pooler a
> background worker and plug in that in a shared memory context that all
> backends connecting to this XC-like-postgres_fdw would use, though
> this is another story, for another time...

Thanks for the history. Very interesting...

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
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