Re: Synchronization levels in SR

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От Boszormenyi Zoltan
Тема Re: Synchronization levels in SR
Дата
Msg-id 4C875F9F.6010406@cybertec.at
обсуждение исходный текст
Ответ на Re: Synchronization levels in SR  (Fujii Masao <masao.fujii@gmail.com>)
Ответы Re: Synchronization levels in SR  (Fujii Masao <masao.fujii@gmail.com>)
Re: Synchronization levels in SR  (Markus Wanner <markus@bluegap.ch>)
Re: Synchronization levels in SR  (Simon Riggs <simon@2ndQuadrant.com>)
Список pgsql-hackers
Fujii Masao írta:
> On Tue, Sep 7, 2010 at 6:02 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>   
>> On Mon, 2010-09-06 at 22:32 +0200, Boszormenyi Zoltan wrote:
>>     
>>> (in commit)
>>> write wal record
>>> release locks/etc   <xact2 can proceed from here
>>> wait for sync ack
>>>
>>> In the first case, the contention is obviously increased.
>>> With this, we are creating more idle time in the server
>>> instead of letting other transactions do their jobs as soon
>>> as possible. The second method was implemented in my
>>> patch. Are there any drawbacks with this?
>>>       
>> Then I respectfully suggest that you're releasing locks too early.
>>
>> Your proposal would allow a 2nd user to see the results of the 1st
>> user's transaction before the 1st user knew about whether it had
>> committed or not.
>>
>> I know why you want that, but I don't think its right.
>>     
>
> Agreed. That's why I put the wait before ProcArrayEndTransaction()
> is called.
>   

Then there is no use to implement individual sync/async
replicated transactions, period. An async replicated transaction
that waits for a sync replicated transaction because of locks
will become implicitely sync. It just waits for another transactions'
sync ack.

Best regards,
Zoltán Böszörményi

> Regards,
>
>   


-- 
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de    http://www.postgresql.at/



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