Re: Transactions involving multiple postgres foreign servers, take 2

On Fri, Jul 17, 2020 at 8:38 AM Masahiko Sawada
<masahiko(dot)sawada(at)2ndquadrant(dot)com> wrote:
>
> On Thu, 16 Jul 2020 at 13:53, tsunakawa(dot)takay(at)fujitsu(dot)com
> <tsunakawa(dot)takay(at)fujitsu(dot)com> wrote:
> >
> > Hi Sawada san,
> >
> >
> > I'm reviewing this patch series, and let me give some initial comments and questions. I'm looking at this with a hope that this will be useful purely as a FDW enhancement for our new use cases, regardless of whether the FDW will be used for Postgres scale-out.
>
> Thank you for reviewing this patch!
>
> Yes, this patch is trying to resolve the generic atomic commit problem
> w.r.t. FDW, and will be useful also for Postgres scale-out.
>

I think it is important to get a consensus on this point. If I
understand correctly, Tsunakawa-San doesn't sound to be convinced that
FDW can be used for postgres scale-out and we are trying to paint this
feature as a step forward in the scale-out direction. As per my
understanding, we don't have a very clear vision whether we will be
able to achieve the other important aspects of scale-out feature like
global visibility if we go in this direction and that is the reason I
have insisted in this and the other related thread [1] to at least
have a high-level idea of the same before going too far with this
patch. It is quite possible that after spending months of efforts to
straighten out this patch/feature, we came to the conclusion that this
need to be re-designed or requires a lot of re-work to ensure that it
can be extended for global visibility. It is better to spend some
effort up front to see if the proposed patch is a stepping stone for
achieving what we want w.r.t postgres scale-out.

[1] - https://www.postgresql.org/message-id/07b2c899-4ed0-4c87-1327-23c750311248%40postgrespro.ru

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com