Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id E8FB21337B93 for ; Wed, 20 Apr 2011 11:41:50 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 90906-06 for ; Wed, 20 Apr 2011 14:41:33 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by mail.postgresql.org (Postfix) with ESMTP id 248021337B68 for ; Wed, 20 Apr 2011 11:41:32 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id p3KEfVtd026405; Wed, 20 Apr 2011 10:41:31 -0400 (EDT) To: Greg Stark cc: Robert Haas , pgsql-hackers@postgresql.org Subject: Re: time-delayed standbys In-reply-to: References: <26007.1303309175@sss.pgh.pa.us> Comments: In-reply-to Greg Stark message dated "Wed, 20 Apr 2011 15:25:09 +0100" Date: Wed, 20 Apr 2011 10:41:31 -0400 Message-ID: <26404.1303310491@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-5 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201104/1028 X-Sequence-Number: 186230 Greg Stark writes: > Ah, so we did put the master's clock in every message? Yes, we did. > Then this > should be simple, no? Just compare the master's timestamp from the > record to the last master's clock seen in the messages. That sounds > equivalent but a lot safer than trying to keep a conversion between > them. Well, the question is what happens after you stop receiving master messages. If you don't make use of the slave's clock somehow, application of WAL will stop dead in the water, which seems unlikely to be what's wanted. regards, tom lane