Re: Transactions involving multiple postgres foreign servers, take 2

On Mon, Sep 7, 2020 at 2:29 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
> IMO it's not easy to commit this 2PC patch at once because it's still large
> and complicated. So I'm thinking it's better to separate the feature into
> several parts and commit them gradually.
>

Hmm, I don't see that we have a consensus on the design and or
interfaces of this patch and without that proceeding for commit
doesn't seem advisable. Here are a few points which I remember offhand
that require more work.
1. There is a competing design proposed and being discussed in another
thread [1] for this purpose. I think both the approaches have pros and
cons but there doesn't seem to be any conclusion yet on which one is
better.
2. In this thread, we have discussed to try integrating this patch
with some other FDWs (say MySQL, mongodb, etc.) to ensure that the
APIs we are exposing are general enough that other FDWs can use them
to implement 2PC. I could see some speculations about the same but no
concrete work on the same has been done.
3. In another thread [1], we have seen that the patch being discussed
in this thread might need to re-designed if we have to use some other
design for global-visibility than what is proposed in that thread. I
think it is quite likely that can happen considering no one is able to
come up with the solution to major design problems spotted in that
patch yet.

It appears to me that even though these points were raised before in
some form we are just trying to bypass them to commit whatever we have
in the current patch which I find quite surprising.

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

--
With Regards,
Amit Kapila.