Re: Quorum commit for multiple synchronous replication.

On Tue, Apr 25, 2017 at 8:07 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Tue, Apr 25, 2017 at 2:09 PM, Kyotaro HORIGUCHI
> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>>
>> I'm not good at composition, so I cannot insist on my
>> proposal. For the convenience of others, here is the proposal
>> from Fujii-san.
>>
>
> Do you see any problem with the below proposal?
> To me, this sounds reasonable.

I agree.

>
>> + A quorum-based synchronous replication is basically more efficient than
>> + a priority-based one when you specify multiple standbys in
>> + <varname>synchronous_standby_names</> and want to replicate
>> + the transactions to some of them synchronously. In this case,
>> + the transactions in a priority-based synchronous replication must wait for
>> + reply from the slowest standby in synchronous standbys chosen based on
>> + their priorities, and which may increase the transaction latencies.
>> + On the other hand, using a quorum-based synchronous replication may
>> + improve those latencies because it makes the transactions wait only for
>> + replies from the requested number of faster standbys in all the listed
>> + standbys, i.e., such slow standby doesn't block the transactions.
>>
>
> Can we do few modifications like:
> improve those latencies --> reduce those latencies
> such slow standby --> a slow standby
>
> --
> With Regards,
> Amit Kapila.
> EnterpriseDB: http://www.enterprisedb.com

Regards,

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