Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VDnwH-0005sc-Og for pgsql-hackers@arkaria.postgresql.org; Mon, 26 Aug 2013 03:58:01 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1VDnwH-00077c-7G for pgsql-hackers@arkaria.postgresql.org; Mon, 26 Aug 2013 03:58:01 +0000 Received: from makus.postgresql.org ([2001:4800:7903:4::125]) by malur.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VDnwF-00073k-DW for pgsql-hackers@postgresql.org; Mon, 26 Aug 2013 03:57:59 +0000 Received: from 99-153-64-76.uvs.austtx.sbcglobal.net ([99.153.64.76] helo=noel.decibel.org) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VDnw8-00034z-83 for pgsql-hackers@postgresql.org; Mon, 26 Aug 2013 03:57:56 +0000 Received: from [192.168.1.70] (adsl-68-255-46-56.dsl.chcgil.ameritech.net [68.255.46.56]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by noel.decibel.org (Postfix) with ESMTPSA id 041EF6D45D; Mon, 26 Aug 2013 03:57:46 +0000 (UTC) Message-ID: <521A8985.2040509@nasby.net> Date: Sun, 25 Aug 2013 17:47:33 -0500 From: Jim Nasby User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Greg Stark CC: Hannu Krosing , Tom Lane , Andres Freund , Alvaro Herrera , Josh Berkus , PostgreSQL-development Subject: Re: pg_system_identifier() References: <5215346B.7070800@dalibo.com> <20130822134205.GC17006@awork2.anarazel.de> <52163222.9030700@agliodbs.com> <20130822155633.GF17006@awork2.anarazel.de> <14611.1377187563@sss.pgh.pa.us> <20130822161839.GG17006@awork2.anarazel.de> <20130822162019.GC10710@eldon.alvh.no-ip.org> <20130822163059.GI17006@awork2.anarazel.de> <15653.1377189456@sss.pgh.pa.us> <52177AD5.5010809@2ndQuadrant.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: 2.6 (++) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-hackers Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org On 8/23/13 11:23 AM, Greg Stark wrote: > This doesn't generate a unique id. You could back up a standby and restore it and point it at the original master and end up with two standbies with the same id. If you want to enforce something unique throughout a cluster, I think we're stuck with having the cluster communicate IDs across an entire cluster. AFAIK that's how both Slony and londiste 3 do it. I think it's also noteworthy that Slony and londiste both rely on the user specifying node identifiers. They don't try to be magic about it. I think there's 2 advantages there: - Code is simpler - Users can choose a naming schema that makes sense for them -- Jim C. Nasby, Data Architect jim@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers