Re: Quorum commit for multiple synchronous replication.

On Thu, Apr 20, 2017 at 9:31 AM, Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> Ok, I got the point.
>
> At Wed, 19 Apr 2017 17:39:01 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> wrote in <20170419.173901.16598616.horiguchi.kyotaro@lab.ntt.co.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