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Re: Quorum commit for multiple synchronous replication.

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Cc: Fujii Masao <masao.fujii@gmail.com>, Sawada Masahiko <sawada.mshk@gmail.com>, Noah Misch <noah@leadboat.com>, Michael Paquier <michael.paquier@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Petr Jelinek <petr@2ndquadrant.com>, Vik Fearing <vik@2ndquadrant.fr>, Simon Riggs <simon@2ndquadrant.com>, Josh Berkus <josh@agliodbs.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-04-25T11:07:58Z
Lists: pgsql-hackers 
On Tue, Apr 25, 2017 at 2:09 PM, Kyotaro HORIGUCHI
<horiguchi.kyotaro@lab.ntt.co.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.

> +     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

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Set the priorities of all quorum synchronous standbys to 1.

  2. Improve documentation and comment for quorum-based sync replication.