From: Simon Riggs <simon@2ndQuadrant.com>
To: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>
Cc: Dimitri Fontaine <dimitri@2ndQuadrant.fr>
Cc: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: greg@2ndQuadrant.com, Josh Berkus <josh@postgresql.org>
Cc: Hannu Krosing <hannu@2ndquadrant.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-hackers@postgresql.org
Subject: Re: Sync Rep Design
Date: Sat, 01 Jan 2011 17:03:48 +0000
Message-ID: <1293901428.1892.60565.camel@ebony> (raw)
In-Reply-To: <4D1F5838.8020509@kaltenbrunner.cc>
References: <1293729972.1892.23804.camel@ebony>
<4D1CC47E.7050207@kaltenbrunner.cc>
<1293735853.1892.24886.camel@ebony>
<AANLkTi=SvN2KQ1Tzh-tRKcXD0i2FyWFBbbR=kXXdepqN@mail.gmail.com>
<4D1D8B2F.5070001@2ndquadrant.com>
<4D1DAB14.5000800@enterprisedb.com>
<1293796137.1892.37313.camel@ebony>
<4D1DCF5A.7070808@enterprisedb.com>
<1293822959.1892.43164.camel@ebony>
<4D1F332A.90306@kaltenbrunner.cc>
<m2ei8wy4ed.fsf@2ndQuadrant.fr>
<4D1F5838.8020509@kaltenbrunner.cc>
On Sat, 2011-01-01 at 17:37 +0100, Stefan Kaltenbrunner wrote:
> On 01/01/2011 05:28 PM, Dimitri Fontaine wrote:
> > Stefan Kaltenbrunner<stefan@kaltenbrunner.cc> writes:
> >> well you keep saying that but to be honest I cannot really even see a
> >> usecase for me - what is "only a random one of a set of servers is sync at
> >> any time and I don't really know which one".
> >
> > It looks easy enough to get to know which one it is. Surely the primary
> > knows and could update something visible through a system view for
> > users? This as been asked for before and I was thinking there was a
> > consensus on this.
>
> well as jeff janes already said - anything that requires the master to
> still exist is not useful for a desaster.
Nobody has suggested that the master needs to still exist after a
disaster.
> Consider the now often
> mentioned 2 sync standby scenario with one standby in the same location
> and one in a secondary location.
> If you have a desaster(fire,water,explosion,admin fail,...) at the
> primary location and you have no access to either the master or the
> standby you will never be sure that the standby on the secondary
> location is actually "in sync" - it could be but you will never know if
> you lost that 1B$ invoice just commited on the master and the closeby
> standby and therefor confirmed to the client...
I've never suggested you configure your systems like that. It would of
course be stupid.
This is not a sensible technical discussion. I'll go back to coding.
--
Simon Riggs http://www.2ndQuadrant.com/books/
PostgreSQL Development, 24x7 Support, Training and Services
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To: pgsql-hackers@postgresql.org
Cc: simon@2ndQuadrant.com, stefan@kaltenbrunner.cc, dimitri@2ndQuadrant.fr, heikki.linnakangas@enterprisedb.com, josh@postgresql.org, hannu@2ndquadrant.com, robertmhaas@gmail.com
Subject: Re: Sync Rep Design
In-Reply-To: <1293901428.1892.60565.camel@ebony>
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