Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 281387CF3 for ; Mon, 10 Oct 2011 16:53:42 +0000 (UTC) Received: (qmail 78810 invoked by uid 500); 10 Oct 2011 16:53:40 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 78770 invoked by uid 500); 10 Oct 2011 16:53:40 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 78762 invoked by uid 99); 10 Oct 2011 16:53:40 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 10 Oct 2011 16:53:40 +0000 X-ASF-Spam-Status: No, hits=-0.7 required=5.0 tests=FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of mohitanchlia@gmail.com designates 209.85.216.44 as permitted sender) Received: from [209.85.216.44] (HELO mail-qw0-f44.google.com) (209.85.216.44) by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 10 Oct 2011 16:53:33 +0000 Received: by qadb12 with SMTP id b12so5329521qad.31 for ; Mon, 10 Oct 2011 09:53:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=mqApaPaNt3marZRlWstQ9i5okfWCWRRAQ4Fk4p7A3l0=; b=HfaIThP6L4hIojUK6P9h8FFbmvi+K8UUbCqblx8MyOxkz/4pY2t1F4MSVg+vbs+M/a 6nYFhgbkpDl7GlIPRPKB7aUW6zjDOQ897pZdHoWP+4JLqcHjt2qgm8LItJPpLu7XxzYH vL6UVuRv9zVTaa0Va3CpW1XWkvXu33bvlH528= MIME-Version: 1.0 Received: by 10.68.35.97 with SMTP id g1mr38376283pbj.38.1318265592382; Mon, 10 Oct 2011 09:53:12 -0700 (PDT) Received: by 10.68.65.166 with HTTP; Mon, 10 Oct 2011 09:53:12 -0700 (PDT) In-Reply-To: <4E91AB18.8000706@sendmail.cz> References: <4E8EA5B3.2020601@sendmail.cz> <4E8EBBD4.7030206@sendmail.cz> <4E8F6908.7020107@sendmail.cz> <4E91AB18.8000706@sendmail.cz> Date: Mon, 10 Oct 2011 09:53:12 -0700 Message-ID: Subject: Re: how to reduce disk read? (and bloom filter performance) From: Mohit Anchlia To: user@cassandra.apache.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Virus-Checked: Checked by ClamAV on apache.org Does it mean you are not updating a row or deleting them? Can you look at JMX values of BloomFilter* ? I don't believe bloom filter false positive % value is configurable. Someone else might be able to throw more light on this. I believe if you want to keep disk seeks to 1 ssTable you will need to compact more often. On Sun, Oct 9, 2011 at 7:09 AM, Radim Kolar wrote: > Dne 7.10.2011 23:16, Mohit Anchlia napsal(a): >> >> You'll see output like: >> >> Offset =A0 =A0 =A0SSTables >> 1 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A08021 >> 2 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0783 >> >> Which means 783 read operations accessed 2 SSTables > > thank you for explaining it to me. I see this: > > Offset =A0 =A0 =A0SSTables > 1 =A0 =A0 =A0 =A0 =A0 =A0 =A059323 > 2 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0857 > 3 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A056 > > it means bloom filter failure ratio over 1%. Cassandra in unit tests expe= cts > bloom filter false positive less than 1.05%. HBase has configurable bloom > filters. You can choose 1% or 0.5% - it can make difference for large cac= he. > > But result is that my poor read performance should not be caused by bloom > filters. >