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Re: Quorum commit for multiple synchronous replication.

Michael Paquier <michael.paquier@gmail.com>

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From: Michael Paquier <michael.paquier@gmail.com>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, Noah Misch <noah@leadboat.com>, Amit Kapila <amit.kapila16@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>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2017-04-14T00:38:13Z
Lists: pgsql-hackers 
On Fri, Apr 14, 2017 at 2:47 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
> I'm thinking that it's less confusing to report always 0 as the priority of
> async standby whatever the setting of synchronous_standby_names is.
> Thought?

Or we could have priority being reported to NULL for async standbys as
well, the priority number has no meaning for them anyway...

> If we adopt this idea, in a quorum-based sync replication, I think that
> the priorities of all the standbys listed in synchronous_standby_names
> should be 1 instead of NULL. That is, those standbys have the same
> (highest) priority, and which means that any of them can be chosen as
> sync standby. Thought?

Mainly my fault here to suggest that standbys in a quorum set should
have a priority set to NULL. My 2c on the matter is that I would be
fine with either having the async standbys having a priority of NULL
or using a priority of 1 for standbys in a quorum set. Though,
honestly, I find that showing a priority number for something where
this has no real meaning is even more confusing..
-- 
Michael

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.