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Message-ID: <4D1F80A9.1020203@enterprisedb.com>
Date: Sat, 01 Jan 2011 21:29:45 +0200
From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
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To: Simon Riggs <simon@2ndQuadrant.com>
CC: Stefan Kaltenbrunner <stefan@kaltenbrunner.cc>,
	Dimitri Fontaine <dimitri@2ndQuadrant.fr>,
	greg@2ndQuadrant.com, Josh Berkus <josh@postgresql.org>,
	Hannu Krosing <hannu@2ndquadrant.com>,
	Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org
Subject: Re: Sync Rep Design
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On 01.01.2011 19:03, Simon Riggs wrote:
> 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.

Dimitri just did, see above. I agree it's not very useful.

I don't think there's any other solution to knowing which standby is 
ahead than connect to both standbys and ask how far each is. I don't see 
a problem with that, whatever middleware handles the failover and 
STONITH etc. should be able to do that too.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com