Re: [HACKERS] Speedup twophase transactions

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От Michael Paquier
Тема Re: [HACKERS] Speedup twophase transactions
Дата
Msg-id CAB7nPqR-bpR=fPsmm0TQzmk7AKOYSq2Zs1yVY-jccTRqHsaz2w@mail.gmail.com
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Ответ на Re: [HACKERS] Speedup twophase transactions  (Simon Riggs <simon@2ndquadrant.com>)
Ответы Re: [HACKERS] Speedup twophase transactions  (Nikhil Sontakke <nikhils@2ndquadrant.com>)
Список pgsql-hackers
On Fri, Jan 27, 2017 at 8:23 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 27 January 2017 at 11:01, Nikhil Sontakke <nikhils@2ndquadrant.com> wrote:
>> The xact_redo code will add prepared transactions to the
>> KnownPreparedList in memory. Earlier it used to create the on-disk 2PC
>> file.
>>
>> At standby promote, the surviving (yet uncommitted) prepared
>> transactions from KnownPreparedList need to be persisted, right?
>
> I don't see why, so please explain or show the error that can be
> caused if we don't.

I agree with Simon here. There is no point to fsync the 2PC files are
in case of an immediate crash after promotion replay will happen from
the last checkpoint, aka the one before the promotion has been
triggered. So there is no point to flush them at promotion, they would
be replayed anyway.
-- 
Michael



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