Re: Quorum commit for multiple synchronous replication.

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.

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center