From: | "Fujii Masao" <masao(dot)fujii(at)gmail(dot)com> |
---|---|
To: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Sync Rep: First Thoughts on Code |
Date: | 2008-12-06 08:29:18 |
Message-ID: | 3f0b79eb0812060029q7e0d450x4fe79a2640990f80@mail.gmail.com |
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Thread: | |
Lists: | pgsql-hackers |
Hi,
On Fri, Dec 5, 2008 at 7:09 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>
> On Fri, 2008-12-05 at 12:09 +0900, Fujii Masao wrote:
>
>> On Thu, Dec 4, 2008 at 6:29 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> > The only sensible settings are
>> > synchronous_commit = on, synchronous_replication = on
>> > synchronous_commit = on, synchronous_replication = off
>> > synchronous_commit = off, synchronous_replication = off
>> >
>> > This doesn't make any sense: (does it??)
>> > synchronous_commit = off, synchronous_replication = on
>>
>> If the standby replies before writing the WAL, that strategy can improve
>> the performance with moderate reliability, and sounds sensible.
>
> Do you think it likely that your replication time is consistently and
> noticeably less than your time-to-disk?
It depends on a system environment.
- How many miles two servers? same rack? separate continent?
- Does system have high-end storage? cheap one?
... etc
>
> On a related thought: presumably we force a sync rep if forceSyncCommit
> is set?
Yes!
Please see RecordTransactionCommit() in xact.c (in my patch).
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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