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 1q69n2-0007Nv-Mk for pgsql-novice@arkaria.postgresql.org; Mon, 05 Jun 2023 12:58:28 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.92) (envelope-from ) id 1q69n0-0004n7-Tv for pgsql-novice@arkaria.postgresql.org; Mon, 05 Jun 2023 12:58:26 +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 1q69n0-0004mx-Kg for pgsql-novice@lists.postgresql.org; Mon, 05 Jun 2023 12:58:26 +0000 Received: from mail-lf1-x135.google.com ([2a00:1450:4864:20::135]) by magus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1q69my-000NT2-Bp for pgsql-novice@lists.postgresql.org; Mon, 05 Jun 2023 12:58:26 +0000 Received: by mail-lf1-x135.google.com with SMTP id 2adb3069b0e04-4f62b512fe2so1150894e87.1 for ; Mon, 05 Jun 2023 05:58:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685969903; x=1688561903; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=GX9dLBB7rpS7idoWKP7+2Ipj6Gr8FlEC7QyP6H0HHpU=; b=Lerm6tPIjkMxSPQj1dUGS70VXnG3vtEu9eMTYtzU/0X9r/PRR1AvqLySnzYoSJQJnE N/C6fOIhhYekgj5pwOG7+uxA/HW/C9ct4GseVj2neYmT4hsXZOcd0/SmVGv0iR7Dk8ks mBhIYgQJsfPoieDhc505KuVlbp0YUiJuJAWA6ezbKdLTu2gXYqzDjL7K7HOYKFti6n9x Iux49duRrUT0xZ7gYnlK0FOXzQylyZYOuWArarbAxjvWkAa89eNjZCzDuWIR/f4LJz0g Cj/eRczxfwpSuRUXNgNVT6nJ36fh0rxaRJqcxZToNxVq01moKPyOzKrEwhbbcMGwNryf lRMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685969903; x=1688561903; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=GX9dLBB7rpS7idoWKP7+2Ipj6Gr8FlEC7QyP6H0HHpU=; b=JANZ9NlsD8qJx69+Un9xk0laeQ64auS99vMD7MKPiX7oKOLXzbSNipHIubaWcmHLgu VgyRCN9RYqn+11OZyUbNWQcnRNd4miGoz3KU5/v+2W5aJjvrDiOls4yMg81iEIT99Gcp SDCaMeQCQ5Gdh03FaKoENOqSsBnjICZpKD3pURENYNtDLEGeDWyjIVpH7+iKCnO9BnMZ lSRo2PTKVv0f4+le+JjjicdkROl5E0zkionXikhOUWnctJ6gVoXXGaCVmpOptQW01eG0 FFkFRhtFG/TNdpB32cxPlJAccN4VrrRgi3rXRt02YCgYaWOZdmWu+/t3ayJRwSYVb0ON wMXw== X-Gm-Message-State: AC+VfDw9qwbnlSfaabJvoMrR9AWNyzTrjTo0Q06IEs7+v8aePPQHiZyp vQyV4Ahv02k2LtPeDmZz7xGF5EgyDGXsCi5Q4UXmo7oW X-Google-Smtp-Source: ACHHUZ6UcQhtSZyIyEvNQarwQS4MDIftki0clnSWtxBmIxkMb6gGi13lhPfCqggMWPdRvxK57LNjIQuZHT3n6kvQLik= X-Received: by 2002:ac2:530b:0:b0:4f3:b6b8:dabb with SMTP id c11-20020ac2530b000000b004f3b6b8dabbmr5066925lfh.13.1685969902399; Mon, 05 Jun 2023 05:58:22 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a05:640c:1c85:b0:1ce:d122:b10b with HTTP; Mon, 5 Jun 2023 05:58:21 -0700 (PDT) In-Reply-To: <1888b7bb7fa.112313046679561.2788161417267896332@trallnag.com> References: <1888b7bb7fa.112313046679561.2788161417267896332@trallnag.com> From: "David G. Johnston" Date: Mon, 5 Jun 2023 05:58:21 -0700 Message-ID: Subject: Re: Does PostgreSQL cache all columns of a table after SELECT? To: Tim Schwenke Cc: pgsql-novice Content-Type: multipart/alternative; boundary="00000000000022755705fd6175b7" List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk --00000000000022755705fd6175b7 Content-Type: text/plain; charset="UTF-8" On Monday, June 5, 2023, Tim Schwenke wrote: > > > Does the cache also contain large_b? Or is only large_a cached? Assumption > is that memory is large enough to fit everything. > > Shared buffers is a page cache. David J. --00000000000022755705fd6175b7 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

On Monday, June 5, 2023, Tim Schwenke <tim@trallnag.com> wrote: