Re: New sync commit mode remote_write

On Thu, Apr 19, 2012 at 12:40, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Thu, Apr 19, 2012 at 10:05 AM, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
>> I admit to not having followed the discussion around the new mode for
>> synchronous_commit very closely, so my apologies if this has been
>> discussed and dismiseed - I blame failing to find it int he archives
>> ;)
>>
>> My understanding from looking at the docs is that
>> synchronous_commit=remote_write will always imply a *local* commit as
>> well.
>>
>> Is there any way to set the system up to do a write to the remote,
>> ensure it's in memory of the remote (remote_write mode, not full sync
>> to disk), but *not* necessarily to the local disk? Meaning we're ok to
>> release the transaction when the data is in memory both locally and
>> remotely but not wait for I/O?
>>
>> Seems there is a pretty large usecase for this particular in our
>> lovely new cloud environments with pathetic I/O performance....
>
> Yeh, its on my TODO list.
>
> What we need to do is to send the last written point as part of the
> replication protocol, so the standby can receive it, yet know not to
> apply it yet in case of crash.
>
> I was expecting that to change as a result of efforts to improve
> WALInsertLock, so I didn't want to do something that would be
> immediately invalidated.

Understood. Something to look forward in 9.3 then :-)

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/