Re: Transactions involving multiple postgres foreign servers

On Thu, Oct 6, 2016 at 1:34 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> On Thu, Oct 6, 2016 at 1:41 PM, Ashutosh Bapat
> <ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
>>>>
>>>> No, the COMMIT returns after the first phase. It can not wait for all
>>>> the foreign servers to complete their second phase
>>>
>>> Hm, it sounds like it's same as normal commit (not 2PC).
>>> What's the difference?
>>>
>>> My understanding is that basically the local server can not return
>>> COMMIT to the client until 2nd phase is completed.
>>
>>
>> If we do that, the local server may not return to the client at all,
>> if the foreign server crashes and never comes up. Practically, it may
>> take much longer to finish a COMMIT, depending upon how long it takes
>> for the foreign server to reply to a COMMIT message.
>
> Yes, I think 2PC behaves so, please refer to [1].
> To prevent local server stops forever due to communication failure.,
> we could provide the timeout on coordinator side or on participant
> side.
>

This too, looks like a heuristic and shouldn't be the default
behaviour and hence not part of the first version of this feature.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company