Re: Transactions involving multiple postgres foreign servers

On Fri, Jan 13, 2017 at 3:20 PM, Ashutosh Bapat
<ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
>>>
>>
>> Long time passed since original patch proposed by Ashutosh, so I
>> explain again about current design and functionality of this feature.
>> If you have any question, please feel free to ask.
>
> Thanks for the summary.
>
>>
>> Parameters
>> ==========
>
> [ snip ]
>
>>
>> Cluster-wide atomic commit
>> =======================
>> Since the distributed transaction commit on foreign servers are
>> executed independently, the transaction that modified data on the
>> multiple foreign servers is not ensured that transaction did either
>> all of them commit or all of them rollback. The patch adds the
>> functionality that guarantees distributed transaction did either
>> commit or rollback on all foreign servers. IOW the goal of this patch
>> is achieving the cluster-wide atomic commit across foreign server that
>> is capable two phase commit protocol.
>
> In [1], I proposed that we solve the problem of supporting PREPARED
> transactions involving foreign servers and in subsequent mail Vinayak
> agreed to that. But this goal has wider scope than that proposal. I am
> fine widening the scope, but then it would again lead to the same
> discussion we had about the big picture. May be you want to share
> design (or point out the parts of this design that will help) for
> solving smaller problem and tone down the patch for the same.
>

Sorry for confuse you. I'm still focusing on solving only that
problem. What I was trying to say is that I think that supporting
PREPARED transaction involving foreign server is the means, not the
end. So once we supports PREPARED transaction involving foreign
servers we can achieve cluster-wide atomic commit in a sense.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center