Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.84_2) (envelope-from ) id 1bv0a5-0005nM-H5 for pgus-general@arkaria.postgresql.org; Fri, 14 Oct 2016 11:23:17 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.84_2) (envelope-from ) id 1bv0a5-0000sA-0U for pgus-general@arkaria.postgresql.org; Fri, 14 Oct 2016 11:23:17 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1bv0a4-0000s3-I6 for pgus-general@postgresql.org; Fri, 14 Oct 2016 11:23:16 +0000 Received: from mail-lf0-x234.google.com ([2a00:1450:4010:c07::234]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.84_2) (envelope-from ) id 1bv0Zy-0002Y6-M3 for pgus-general@postgresql.org; Fri, 14 Oct 2016 11:23:15 +0000 Received: by mail-lf0-x234.google.com with SMTP id b81so188188004lfe.1 for ; Fri, 14 Oct 2016 04:23:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:subject :content-transfer-encoding; bh=WhB/aAPGJCz9Qmoc7mmAX73LY1tcGgfvKdXy9L3kG7Q=; b=yPLOD+MtvmBw6MuAN1o9UAwpZBEO1l5hyv687oDaTd83+rj2X6FauMFTpUFB9RW5x7 OWc6Ao9SM3vAxYiiAjgEhHGP+jbe834mM0EVWEdYwMM69ODGSggeZ1+fH4waiy/r1T3Y btUT+uuXYF6RBoaG+0XyBalI8vvj50pZC4YfwV5Y9tmb9enpjveU0LI78hDF6I5Iqn9M eiWfZZnQEZOM+hGnE03i1LuwuLS0uIXRco+sv1ezDOjCfaUKEjCcSOQ9W+AfObmrUhvx O0dvI+/D6GEULilOnWSlAiuYl4WclHXzk621B34mFni4lB5KMWP6TcnCWFMyBAjXJZvF mhSw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to :subject:content-transfer-encoding; bh=WhB/aAPGJCz9Qmoc7mmAX73LY1tcGgfvKdXy9L3kG7Q=; b=S5dNHGTCDBr2NnO7ILrYukmay6J4ouMEBwV6kkMirqbdXKJy90z2qz6/JfSDUoIo6g 0l315A33VzRlvUnLZIkmXizFg9hUFUSFTCX0sfUNb76HRcDcrEzF95n3ec+itfp6EnM8 8cgV5fYmt1A46GkkRBhigt/5/pWZ3kRunMDPgoT61Y5dDhJdPCknKaeREgWPlxlj47Zg JS0yOjw7tyMnmF8iGDo+euVHosFoEfdgRwpQNzJXWIYvKdd38GbJHvCUDDvSbq6BTu73 f6N5Ubcv974Qu6+SIUbGQyk665NfSI6Rgb9uXW/V+uH+bJNeWQCTPHhB383L6vX54B9I nnXA== X-Gm-Message-State: AA6/9Rnvf6V+1iL4sIZ2tPDawRnG5X30cK89s5rSqvybl6cVKLJzMCrUb417D8OpwJx1mQ== X-Received: by 10.28.224.215 with SMTP id x206mr1303852wmg.77.1476444187288; Fri, 14 Oct 2016 04:23:07 -0700 (PDT) Received: from [192.168.0.100] ([87.18.244.4]) by smtp.gmail.com with ESMTPSA id qq7sm31012301wjc.30.2016.10.14.04.23.06 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 14 Oct 2016 04:23:06 -0700 (PDT) Message-ID: <5800C00F.4030208@gmail.com> Date: Fri, 14 Oct 2016 13:22:55 +0200 From: "t.dalpozzo@gmail.com" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.8.0 MIME-Version: 1.0 To: pgus-general@postgresql.org Subject: journaled FS and and WAL Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -2.7 (--) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgus-general Precedence: bulk Sender: pgus-general-owner@postgresql.org Hi, two question related to the WAL. 1) I read in the doc that journaled FS is not important as WAL is journaling itself. But who garantees that the WAL is written correctly? I know that it's sequential and a partial update of WAL can be discarded after a restart. But am I sure that without a journaled FS, if there is a crash during the WAL update, nothing already updated in the WAL before my commit can get corrupted? 2) Let's suppose that I have one database, one table of 100000 rows, each 256 bytes. Now, in a single SQL commit, I update row 10, row 30000 and row 80000. How much should I expect the WAL increase by? (supposing no WAL segments will be deleted). I could guess 8192x3 but I'm not sure Regards Pupillo -- Sent via pgus-general mailing list (pgus-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgus-general