Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Wx4FH-0003ox-6e for pgsql-hackers@arkaria.postgresql.org; Wed, 18 Jun 2014 01:00:59 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1Wx4FG-0005oO-MO for pgsql-hackers@arkaria.postgresql.org; Wed, 18 Jun 2014 01:00:58 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1Wx4FF-0005oG-KM for pgsql-hackers@postgresql.org; Wed, 18 Jun 2014 01:00:57 +0000 Received: from mout.kundenserver.de ([212.227.17.13]) by magus.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1Wx4FC-0007fd-8F for pgsql-hackers@postgresql.org; Wed, 18 Jun 2014 01:00:56 +0000 Received: from ayaki.localdomain (106-69-164-206.dyn.iinet.net.au [106.69.164.206]) by mrelayeu.kundenserver.de (node=mreue103) with ESMTP (Nemesis) id 0LgNts-1WKPUc1h0G-00nhaZ; Wed, 18 Jun 2014 03:00:46 +0200 Message-ID: <53A0E4B5.3090207@2ndquadrant.com> Date: Wed, 18 Jun 2014 09:00:37 +0800 From: Craig Ringer Organization: 2nd Quadrant User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Robert Haas CC: Heikki Linnakangas , Greg Stark , Alvaro Herrera , Andres Freund , Bruce Momjian , Rajeev rastogi , Ants Aasma , PostgreSQL-development , Markus Wanner Subject: Re: Proposal for CSN based snapshots References: <51B1CB35.4050406@bluegap.ch> <51B6C97B.1070000@bluegap.ch> <5370D323.1070606@vmware.com> <20140512144112.GB9619@awork2.anarazel.de> <5370E267.2020904@vmware.com> <20140515183436.GD25053@momjian.us> <20140515200632.GB16014@awork2.anarazel.de> <20140515213714.GB7857@eldon.alvh.no-ip.org> <53889CCB.7030005@vmware.com> <5388A063.5000209@vmware.com> <539E7985.5090801@2ndquadrant.com> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Provags-ID: V02:K0:zFVxYFyCOs9/KkBA1zeMH++4/Fy1GU8c9Ns6OO2SXaH NELy7HpcVinvQwbH5T84GF+AUfUNf2ROqDnEREtoE5cVcTvjYR BwzGaDIlq2QyyuDQuQxqd1AyIhxSTd4eJETkElfL73jwmzf0Pm nmWeBFY7U/iuKIVLZQoznebSZP6AuxB7GI2LnsdZobs/mebILf ARMa6Ux+4Tu8y1LkA94Zfo+ebfW3tbo5NoGKV2KvBngf2s/7wM 5GB3UedZHaUhGEshCyfFtrjj/aE6oilecc6K9y/Ua/RTfMMojw pxG1c9XODEWawjHxH+VyFzFD4iyoOFLZbVs4mu7R776CjxciuV gOkqPsX6w7hliY6t8fGsxUt3OfQCsQiHFkhFrRmK3 X-Pg-Spam-Score: -1.9 (-) 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 06/18/2014 12:41 AM, Robert Haas wrote: > On Mon, Jun 16, 2014 at 12:58 AM, Craig Ringer wrote: >> > On 05/30/2014 11:14 PM, Heikki Linnakangas wrote: >>> >> Yeah. To recap, the failure mode is that if the master crashes and >>> >> restarts, the transaction becomes visible in the master even though it >>> >> was never replicated. >> > >> > Wouldn't another pg_clog bit for the transaction be able to sort that out? > How? A flag to indicate that the tx is locally committed but hasn't been confirmed by a streaming synchronous replica, so it must not become visible until the replica confirms it or SR is disabled. Then scan pg_clog on start / replica connect and ask the replica to confirm local commit for those tx's. No? -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers