Re: Transactions involving multiple postgres foreign servers

On Fri, Jan 13, 2017 at 3:48 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> 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.
>

Attached updated patches. I fixed some bugs and add 003 patch that
adds TAP test for foreign transaction.
003 patch depends 000 and 001 patch.

Please give me feedback.

Regards,

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