Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qe0bM-005Tm3-T6 for pgsql-hackers@arkaria.postgresql.org; Wed, 06 Sep 2023 22:02:20 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1qe0bK-00DRrY-3T for pgsql-hackers@arkaria.postgresql.org; Wed, 06 Sep 2023 22:02:17 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qe0bJ-00DRrO-P8 for pgsql-hackers@lists.postgresql.org; Wed, 06 Sep 2023 22:02:17 +0000 Received: from sss.pgh.pa.us ([68.162.161.243]) by magus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qe0bE-003Uxw-Qh for pgsql-hackers@lists.postgresql.org; Wed, 06 Sep 2023 22:02:16 +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 386M1r2e1578569; Wed, 6 Sep 2023 18:01:53 -0400 From: Tom Lane To: Andres Freund cc: Heikki Linnakangas , Alvaro Herrera , Masahiko Sawada , David Rowley , Dean Rasheed , Jakub Wartak , Andrew Dunstan , Peter Eisentraut , PostgreSQL Hackers Subject: Re: Performance degradation on concurrent COPY into a single relation in PG16. In-reply-to: <20230816225432.fibahevlqsssj2hv@awork3.anarazel.de> References: <20230812200504.li5vomg36j2tretx@awork3.anarazel.de> <20230816111546.wrkepwwjwfuottpq@alvherre.pgsql> <20230816225432.fibahevlqsssj2hv@awork3.anarazel.de> Comments: In-reply-to Andres Freund message dated "Wed, 16 Aug 2023 15:54:32 -0700" MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1578567.1694037713.1@sss.pgh.pa.us> Content-Transfer-Encoding: quoted-printable Date: Wed, 06 Sep 2023 18:01:53 -0400 Message-ID: <1578568.1694037713@sss.pgh.pa.us> List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk Andres Freund writes: > On 2023-08-16 13:15:46 +0200, Alvaro Herrera wrote: >> Since the wins from this patch were replicated and it has been pushed, = I >> understand that this open item can be marked as closed, so I've done >> that. > Thanks! It turns out that this patch is what's making buildfarm member chipmunk fail in contrib/pg_visibility [1]. That's easily reproduced by running the test with shared_buffers =3D 10MB. I didn't dig further than the "git bisect" result: $ git bisect bad 82a4edabd272f70d044faec8cf7fd1eab92d9991 is the first bad commit commit 82a4edabd272f70d044faec8cf7fd1eab92d9991 Author: Andres Freund Date: Mon Aug 14 09:54:03 2023 -0700 hio: Take number of prior relation extensions into account but I imagine the problem is that the patch's more aggressive relation-extension heuristic is causing the table to have more pages than the test case expects. Is it really a good idea for such a heuristic to depend on shared_buffers? If you don't want to change the heuristic then we'll have to find a way to tweak this test to avoid it. regards, tom lane [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dchipmunk&dt=3D= 2023-09-06%2014%3A14%3A51