Re: Replication with 9.4

(Seems like you forgot to push the Reply-all button)

On Sun, Oct 4, 2015 at 7:01 PM, Madovsky wrote:
> On 10/3/2015 3:30 PM, Michael Paquier wrote:
>>  and no reason is given to justify *why* this would be needed in your case
> reason for a choice can be often an issue for other :D
>
> I thought that postgresql 9.4  user could change on the fly with
> synchronous_commit from local to on for ex
> which hotstandby would become in sync and which in async to avoid a big
> latency in case of let's say 100 hot standby.
> it was an idea, a concept to let the master write and update the nodes, like
> a queen bee ;)
> but I'm afraid it's not possible, so maybe future version of pg will do it,
> for now  read from the master is my only solution.

Well, Thomas Munro (adding him in CC) has sent for integration with
9.6 a patch that would cover your need, by adding to
synchronous_commit a mode called 'apply', in which case a master would
wait for the transaction to be applied on standby before committing
locally:
http://www.postgresql.org/message-id/CAEepm=1fqkivL4V-OTPHwSgw4aF9HcoGiMrCW-yBtjipX9gsag@mail.gmail.com
Perhaps you could help with the review of the patch, this has stalled
a bit lately.
Regards,
--
Michael