Subject: Re: Sync Rep Design
From: Simon Riggs <simon@2ndQuadrant.com>
To: Robert Treat <rob@xzilla.net>
Cc: pgsql-hackers@postgresql.org
In-Reply-To: <AANLkTi=dr9TuYRLMWjPkJdL1Jjg+TAJXPJQbLGiN1Pag@mail.gmail.com>
References: <1293729972.1892.23804.camel@ebony>
	<4D1CC47E.7050207@kaltenbrunner.cc> <1293735853.1892.24886.camel@ebony>
	<AANLkTi=dr9TuYRLMWjPkJdL1Jjg+TAJXPJQbLGiN1Pag@mail.gmail.com>
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Date: Thu, 30 Dec 2010 20:36:30 +0000
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On Thu, 2010-12-30 at 15:07 -0500, Robert Treat wrote:
> > If more than one standby server specifies synchronous_replication,
> then
> > whichever standby replies first will release waiting commits.

> I don't want you to think I am setting an expectation, but I'm curious
> about the possibility of requiring more than 1 server to reply?

I was initially interested in this myself, but after a long discussion
on "quorum commit" it was decided to go with "first past post".

That is easier to manage, requires one less parameter, performs better
and doesn't really add that much additional confidence.

It was also discussed that we would have a plugin API, but I'm less sure
about that now. Perhaps we can add that option in the future, but its
not high on my list of things for this release.

-- 
 Simon Riggs           http://www.2ndQuadrant.com/books/
 PostgreSQL Development, 24x7 Support, Training and Services