Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 44486 invoked from network); 13 Jan 2011 19:05:32 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 13 Jan 2011 19:05:32 -0000 Received: (qmail 4393 invoked by uid 500); 13 Jan 2011 19:05:31 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 4345 invoked by uid 500); 13 Jan 2011 19:05:30 -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 4337 invoked by uid 99); 13 Jan 2011 19:05:30 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 13 Jan 2011 19:05:30 +0000 X-ASF-Spam-Status: No, hits=-0.0 required=10.0 tests=SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: local policy) Received: from [12.232.165.2] (HELO agops01.inq.com) (12.232.165.2) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 13 Jan 2011 19:05:24 +0000 Received: from agmail02.corp.inq.com ([172.26.104.32]) by agops01.inq.com (8.13.8/8.13.8) with ESMTP id p0DJ53Q1020478 for ; Thu, 13 Jan 2011 11:05:03 -0800 X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: RE: cassandra row cache Date: Thu, 13 Jan 2011 11:05:02 -0800 Message-ID: In-Reply-To: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: cassandra row cache Thread-Index: AcuzVE9BjgavORbVSWSpKLtzut9G7QAAGx3g References: From: "Saket Joshi" To: X-Virus-Checked: Checked by ClamAV on apache.org Yes it does change.=20 -----Original Message----- From: Jonathan Ellis [mailto:jbellis@gmail.com]=20 Sent: Thursday, January 13, 2011 11:01 AM To: user Subject: Re: cassandra row cache does the cache size change between 2nd and 3rd time? On Thu, Jan 13, 2011 at 10:47 AM, Saket Joshi wrote: > Hi, > > I am running a 15 node cluster ,version 0.6.8, Linux 64bit OS, using mmap > I/O, 6GB ram allocated. I have row cache enabled to 80000 keys (mean row > size is 2KB). I am observing a strange behaviour.. I query for 1.6 Million > rows across the cluster and time taken is around 40 mins , I query the same > data again , the time now is 25 mins to fetch data (i am expecting the cache > to be warm now) , but i see row cache hit rate around 30% . Now i request > the same data 3rd time, time to fetch is under 4 mins and cache hit ratios > are 99% ... Does any one have an idea why this may be happening ? > > > > > > Thanks, > > Saket --=20 Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com