Re: Quorum commit for multiple synchronous replication.

On Thu, Apr 20, 2017 at 9:31 AM, Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> Ok, I got the point.
>
> At Wed, 19 Apr 2017 17:39:01 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20170419(dot)173901(dot)16598616(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
>> > >> | <para>
>> > >> | Quorum-based synchronous replication is basically more
>> > >> | efficient than priority-based one when you specify multiple
>> > >> | standbys in <varname>synchronous_standby_names</> and want
>> > >> | to synchronously replicate transactions to two or more of
>> > >> | them.
>
> "Some" means "not all".
>
>> > >> | In the priority-based case, the replication master
>> > >> | must wait for a reply from the slowest standby in the
>> > >> | required number of standbys in priority order, which may
>> > >> | slower than the rest.
>
>
> Quorum-based synchronous replication is expected to be more
> efficient than priority-based one when your master doesn't need
> to be in sync with all of the nominated standbys by
> <varname>synchronous_standby_names</>. While quorum-based
> replication master waits only for a specified number of fastest
> standbys, priority-based replicatoin master must wait for
> standbys at the top of the list, which may be slower than the
> rest.

This description looks good to me. I've updated the patch based on
this description and attached it.

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center