Horton

Re: Standalone synchronous master

Peter Eisentraut <peter_e@gmx.net>

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From: Peter Eisentraut <peter_e@gmx.net>
To: Stephen Frost <sfrost@snowman.net>
Cc: Andres Freund <andres@2ndquadrant.com>, "Joshua D. Drake" <jd@commandprompt.com>, Tom Lane <tgl@sss.pgh.pa.us>, Kevin Grittner <kgrittn@ymail.com>, Bruce Momjian <bruce@momjian.us>, Heikki Linnakangas <hlinnakangas@vmware.com>, Simon Riggs <simon@2ndQuadrant.com>, Rajeev rastogi <rajeev.rastogi@huawei.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2014-01-11T01:21:44Z
Lists: pgsql-hackers 
On Wed, 2014-01-08 at 17:56 -0500, Stephen Frost wrote:
> * Andres Freund (andres@2ndquadrant.com) wrote:
> > That's why you should configure a second standby as another (candidate)
> > synchronous replica, also listed in synchronous_standby_names.
> 
> Perhaps we should stress in the docs that this is, in fact, the *only*
> reasonable mode in which to run with sync rep on?  Where there are
> multiple replicas, because otherwise Drake is correct that you'll just
> end up having both nodes go offline if the slave fails.

It's not unreasonable to run with only two if the writers are consuming
from a reliable message queue (or another system that maintains its own
reliable persistence).  Then you can just continue processing messages
after you have repaired your replication pair.