Re: Sync Rep: First Thoughts on Code

Hi,

On Fri, Dec 5, 2008 at 7:09 PM, Simon Riggs <simon@2ndquadrant.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@2ndquadrant.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