From user-return-34926-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Thu Jun 27 18:41:27 2013 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 2F785100E8 for ; Thu, 27 Jun 2013 18:41:27 +0000 (UTC) Received: (qmail 4481 invoked by uid 500); 27 Jun 2013 18:41:24 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 4457 invoked by uid 500); 27 Jun 2013 18:41:24 -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 4449 invoked by uid 99); 27 Jun 2013 18:41:24 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 27 Jun 2013 18:41:24 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: local policy) Received: from [216.109.115.239] (HELO nm50-vm8.bullet.mail.bf1.yahoo.com) (216.109.115.239) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 27 Jun 2013 18:41:15 +0000 Received: from [98.139.212.145] by nm50.bullet.mail.bf1.yahoo.com with NNFMP; 27 Jun 2013 18:40:54 -0000 Received: from [98.139.212.232] by tm2.bullet.mail.bf1.yahoo.com with NNFMP; 27 Jun 2013 18:40:54 -0000 Received: from [127.0.0.1] by omp1041.mail.bf1.yahoo.com with NNFMP; 27 Jun 2013 18:40:54 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 671748.58543.bm@omp1041.mail.bf1.yahoo.com Received: (qmail 86505 invoked by uid 60001); 27 Jun 2013 18:40:54 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1372358454; bh=ABwbNSshpsUFfipR4jcjFVpwRot1sTT3WYQTlPw9Llg=; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=CX7IRXqVa5pLLH3QNlkeeBWebUQQLpFMvLX1eHBL0ssQmN4Fl7IxJdSfnZ+SKfesu60Vgb8B1COnZvWqfBeq8HlEojZWX44JDttPUF0yZ9cBL8RnYrOirVUK9PjX81Lt1BdS9z95sagcjnIJl+ggWC37GnMImN+tEUC+4TCEc+Y= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=QvDTNW1CnwClUVwQ34ob6Mrm1i9eS2rtM/j9O9zYdI/8xNK+97OkjKQkikmmS4jDynyh0jzc+c+UQeZ58sE6ejg0UOfk3h5T81EnUobJUjjfy3F0h6Y4q141nFiC3Y+5BGMdnx8MEK7cqcSa+KHQ75ea+BlPApnb8k5u1V2Tlfc=; X-YMail-OSG: 4jjh2fIVM1ny3LE3rwsYzlvYYRNBdWsDzvnRBu5F6OlPIGR u.ONm1Ekk_w.F8QxdzYP2cQtYr0Gc4etRftpicYLHum9QtHIwimNZ5ECs._h IltFd.3V6CfGGc657EjxZD87z8rrbHgDYZwPVhxpY2tY9Ushr6Yh2as_R3O5 WbTG6vsZP6zdzSizFwF0mz4wrCuhpZC8WIb_8I.ldh8u4XL7czbawKMdo1Lp EVJ6CIivaTA4IiRkQ_H4BrcvRq3rr5OzFSn0AcxqdaLdTya55n9fIANpXvIo HbUeyjXuoJAD1WMQ15XG1ZQhKmw6zS8GMGc5kA_0QMtsBpL7CdVzcnXS7bcm b9OToOwFDcyrmt9S_BZkvm9CEGwAB9Q8mLoB03dEme7NBYW8gRTCTyT0cSho SID2iwh4_POUFuUCHr9nchV4tkSImWyaDJkGxcKxjLlCaG8vc3e7wueCIDG2 3hgP4ERC1CX.a_Y5iBDmYFkuBercmxI0BO8ZN8xYqxNm1gUG6bg8_jRlC5MB FbLutPXFLUDnikEp0i7AAQdpRN5.COo2wjzFRoQtg Received: from [209.131.62.116] by web142804.mail.bf1.yahoo.com via HTTP; Thu, 27 Jun 2013 11:40:54 PDT X-Rocket-MIMEInfo: 002.001,SGksCgrCoMKgwqAgV2UgYXJlIHVzaW5nIExldmVsZWQgQ29tcGFjdGlvbiB3aXRoIENhc3NhbmRyYSAxLjIuNS4gT3VyIHNzdGFibGUgc2l6ZSBpcyAxMDBNLiBPbiBlYWNoIG5vZGUsCndlIGhhdmUgYW55d2hlcmUgZnJvbSA3MDArIHRvIDgwMCsgc3N0YWJsZXMgKGZvciBhbGwgbGV2ZWxzKS4gVGhlIGJsb29tX2ZpbHRlcl9mcF9jaGFuY2UgaXMgc2V0IGF0IDAuMDAwNzQ0LgoKwqAgRm9yIHJlYWQgcmVxdWVzdHMgdGhhdCBhc2sgZm9yIGV4aXN0aW5nIHJvdyByZWNvcmRzLCB0aGUgbGF0ZW5jeSBpcyBncmUBMAEBAQE- X-Mailer: YahooMailWebService/0.8.148.557 Message-ID: <1372358454.85687.YahooMailNeo@web142804.mail.bf1.yahoo.com> Date: Thu, 27 Jun 2013 11:40:54 -0700 (PDT) From: Bao Le Reply-To: Bao Le Subject: High-read latency for non-existing rows with LCS and 1.2.5 To: user@cassandra.apache.org MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-2129327256-264758783-1372358454=:85687" X-Virus-Checked: Checked by ClamAV on apache.org ---2129327256-264758783-1372358454=:85687 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi,=0A=0A=A0=A0=A0 We are using Leveled Compaction with Cassandra 1.2.5. Ou= r sstable size is 100M. On each node,=0Awe have anywhere from 700+ to 800+ = sstables (for all levels). The bloom_filter_fp_chance is set at 0.000744.= =0A=0A=A0 For read requests that ask for existing row records, the latency = is great, mostly under 20 milliseconds with key cache and row cache set. Fo= r read requests that ask for non-existing row records (not because of delet= es, but rather, have never been in the system to start with), the latency i= s running into hundreds of milliseconds and sometimes seconds.=0A=0A=A0 Jus= t wonder if anyone has come across this before and has some pointers on how= to reduce the latency in this case.=0A=0AThanks=0ABao ---2129327256-264758783-1372358454=:85687 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi,

 &nbs= p;  We are using Leveled Compaction with Cassandra 1.2.5. Our sstable = size is 100M. On each node,
we have anywhere from 700+ to 800+ sstables = (for all levels). The bloom_filter_fp_chance is set at 0.000744.

&nb= sp; For read requests that ask for existing row records, the latency is gre= at, mostly under 20 milliseconds with key cache and row cache set. For read= requests that ask for non-existing row records (not because of deletes, bu= t rather, have never been in the system to start with), the latency is runn= ing into hundreds of milliseconds and sometimes seconds.

  Just= wonder if anyone has come across this before and has some pointers on how = to reduce the latency in this case.

Thanks
Bao


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