Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1ihCaq-0001MG-8s for pgsql-performance@arkaria.postgresql.org; Tue, 17 Dec 2019 13:08:52 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.89) (envelope-from ) id 1ihCao-0002C0-E0 for pgsql-performance@arkaria.postgresql.org; Tue, 17 Dec 2019 13:08:50 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1ihCan-0002Bt-Vr for pgsql-performance@lists.postgresql.org; Tue, 17 Dec 2019 13:08:50 +0000 Received: from mail-wm1-x343.google.com ([2a00:1450:4864:20::343]) by magus.postgresql.org with esmtps (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1ihCag-0001y3-4U for pgsql-performance@lists.postgresql.org; Tue, 17 Dec 2019 13:08:48 +0000 Received: by mail-wm1-x343.google.com with SMTP id t14so3076905wmi.5 for ; Tue, 17 Dec 2019 05:08:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cybertec-at.20150623.gappssmtp.com; s=20150623; h=message-id:subject:from:to:cc:date:in-reply-to:references :user-agent:mime-version:content-transfer-encoding; bh=baeFRYYKgSJzlS57imVMVDD2qcWb1y8mLYx17ZAolrk=; b=cG8Wddc1ZzfNwgKcXocHhx9B+RsFZDMmJEz/Md116foNK1uk2e/xsaRCbfyRigYCQy 2GX2naSBOKVagoNEqjG99YqU1n+FUS63rvDAqixwIHbP1dR4+wnW4i3/lecDvHo8+l67 DgGqAc3ZhkBXBoCWi8b5xPuqmNFntDnni6C6mSLcQmoabYom3hcc3x32S+qQImOfhlQj RZAgBuuGO0i+M97V/AaMnc0zwTCnVQ3FUszSa+ueIOvhqhyxEgO1sw82Y1ewnCKAZiYG crnCSWLvUmOrNkhSHJCy1vI2X4P2PECzWsgghk6LPLnkwX779+CswipgmNUaMDo6vmm3 mUxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:user-agent:mime-version:content-transfer-encoding; bh=baeFRYYKgSJzlS57imVMVDD2qcWb1y8mLYx17ZAolrk=; b=UMtT1nbaDZ8I7aRVmgTU6t8WJ/7RZlr+HUdksrySvcck99MtNfwuNkkcm2Rkz7pCjS 1dXPGCMAHh+EAtQ0o4lOw6suMM/eaBGKoroEVMaG66w61ExTiaQsXTZovI+dKVRLXQVr LJp2E83QEIR/meE7wbN0zjm+oJ9hylObDkf+1RYQCoA4o5IVKa/48aHk4KmpwVQ9gzKx 0dg0Stj+RAPOBKXRVLjD8DF/krH6x5n2m/6PC8S5MnW+r60UllyfJUgCO5CbNexvrBvE vCDCrrMTzCxpd6QA0SKGyMQGaZ7u6MCpjHuQaJnAPU7pcdnXgNIX14ZSvZw39jauXLxr 8WUA== X-Gm-Message-State: APjAAAV3pbtqoRt+woeSRCoMH+GIB0tCAA8sAXx3OabZvIuVxvfYUCcO gcaDY+UeEbVgw00oXTRB0K6z4Q== X-Google-Smtp-Source: APXvYqwOx7VksIUTnRhDfz66sjYh2MmxYuhE24jP52qcyzqLa9RvwjoqFqsdHN1ZlpQ9Mu03veH/pg== X-Received: by 2002:a1c:2155:: with SMTP id h82mr5586490wmh.21.1576588121128; Tue, 17 Dec 2019 05:08:41 -0800 (PST) Received: from localhost.localdomain ([212.186.219.234]) by smtp.gmail.com with ESMTPSA id a16sm25341357wrt.37.2019.12.17.05.08.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Dec 2019 05:08:40 -0800 (PST) Message-ID: Subject: Re: Consecutive Query Executions with Increasing Execution Time From: Laurenz Albe To: Tom Lane , Peter Geoghegan Cc: Shijia Wei , pgsql-performance@lists.postgresql.org Date: Tue, 17 Dec 2019 14:08:39 +0100 In-Reply-To: <19575.1576529417@sss.pgh.pa.us> References: <19575.1576529417@sss.pgh.pa.us> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.32.5 (3.32.5-1.fc30) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On Mon, 2019-12-16 at 15:50 -0500, Tom Lane wrote: > Peter Geoghegan writes: > > Why do the first and the twentieth executions of the query have almost > > identical "buffers shared/read" numbers? That seems odd. > > It's repeat execution of the same query, so that doesn't seem odd to me. Really? Shouldn't the blocks be in shared buffers after a couple of executions? Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com