Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lME13-000182-MM for pgsql-hackers@arkaria.postgresql.org; Tue, 16 Mar 2021 18:02:01 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.92) (envelope-from ) id 1lME12-0005PZ-JA for pgsql-hackers@arkaria.postgresql.org; Tue, 16 Mar 2021 18:02:00 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lME12-0005PM-CZ for pgsql-hackers@lists.postgresql.org; Tue, 16 Mar 2021 18:02:00 +0000 Received: from sss.pgh.pa.us ([66.207.139.130]) by magus.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lME10-0003gu-DP for pgsql-hackers@postgresql.org; Tue, 16 Mar 2021 18:02:00 +0000 Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1]) by sss.pgh.pa.us (8.15.2/8.15.2) with ESMTP id 12GI1lX03376187; Tue, 16 Mar 2021 14:01:47 -0400 From: Tom Lane To: Mark Dilger cc: Robert Haas , Noah Misch , Peter Geoghegan , Thomas Munro , "Andrey M. Borodin" , Stephen Frost , Michael Paquier , Amul Sul , Dilip Kumar , Andres Freund , PostgreSQL-development Subject: Re: pg_amcheck contrib application In-reply-to: <3360174.1615916917@sss.pgh.pa.us> References: <9E76E46A-48B2-4869-BD0C-422204C1F767@enterprisedb.com> <20210313184612.GA3195145@rfd.leadboat.com> <930621E5-5D10-456D-8CE4-CF629A6C4669@enterprisedb.com> <20210313191841.GB3195145@rfd.leadboat.com> <3012106.1615827854@sss.pgh.pa.us> <3053552.1615834640@sss.pgh.pa.us> <20210316060913.GA3323238@rfd.leadboat.com> <7BCE9084-9381-471F-90F2-FAD99B7FE3DB@enterprisedb.com> <3254547.1615910855@sss.pgh.pa.us> <7CFAF7EF-4EA7-4CB6-B2C7-EC7F4512AE50@enterprisedb.com> <16B79A18-48F3-404D-8DC5-53528E85A7AC@enterprisedb.com> <3360174.1615916917@sss.pgh.pa.us> Comments: In-reply-to Tom Lane message dated "Tue, 16 Mar 2021 13:48:37 -0400" MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3376185.1615917707.1@sss.pgh.pa.us> Date: Tue, 16 Mar 2021 14:01:47 -0400 Message-ID: <3376186.1615917707@sss.pgh.pa.us> List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk ... btw, I now see that tern and hornet are passing this test at least as much as they're failing, proving that there's some timing or random chance involved. That doesn't completely eliminate the idea that there may be an architecture component to the issue, but it sure reduces its credibility. I now believe the theory that the triggering condition is an auto-analyze happening at the right time, and populating pg_statistic with some data that other runs don't see. regards, tom lane