Return-Path: Delivered-To: apmail-incubator-cassandra-user-archive@minotaur.apache.org Received: (qmail 15210 invoked from network); 10 Mar 2010 16:02:10 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 10 Mar 2010 16:02:10 -0000 Received: (qmail 93754 invoked by uid 500); 10 Mar 2010 16:01:39 -0000 Delivered-To: apmail-incubator-cassandra-user-archive@incubator.apache.org Received: (qmail 93711 invoked by uid 500); 10 Mar 2010 16:01:39 -0000 Mailing-List: contact cassandra-user-help@incubator.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: cassandra-user@incubator.apache.org Delivered-To: mailing list cassandra-user@incubator.apache.org Received: (qmail 93703 invoked by uid 99); 10 Mar 2010 16:01:39 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 10 Mar 2010 16:01:39 +0000 X-ASF-Spam-Status: No, hits=0.0 required=10.0 tests=FREEMAIL_FROM,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of jbellis@gmail.com designates 74.125.82.175 as permitted sender) Received: from [74.125.82.175] (HELO mail-wy0-f175.google.com) (74.125.82.175) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 10 Mar 2010 16:01:37 +0000 Received: by wyb28 with SMTP id 28so623046wyb.6 for ; Wed, 10 Mar 2010 08:01:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :from:date:message-id:subject:to:content-type; bh=HFH79CEF/LG+ioXNq/KVdeYhL4Hc2Ii7Sj9dHjxygcA=; b=tkOPBLOi9KzDlJYwEBLLjyQsOFjpkrq2RGMLIJk6tVnRPoweRtR2MGnKHHI3MrGtWE VH6B81HrkOAr8sM03evu0iwNHZEZDQbwSaYP2qThcTMIHyMiOW8gBaI/P48IuQ9QftSb kFyK1eJYoXd0r2v7e21s+mklPnuh7MIaw7oBQ= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; b=LlGm2nfXVSvnXhJfk6ptJRPfXNautvnO5dt2sqA0cky90AHMCd7V5b3h5FOCTJB06+ MvQHiW/OxAjKoXDjdoHUnwfjZmZ2jqdojNk0qFEVT/digo+FR5NY9B40QPbYMrFwrQHH FEASqLkqV6SAliYPBnPrMN+z0uJ34Fw5m5wCY= MIME-Version: 1.0 Received: by 10.216.88.205 with SMTP id a55mr1037712wef.122.1268236876181; Wed, 10 Mar 2010 08:01:16 -0800 (PST) In-Reply-To: References: <002d01cac069$1c924ed0$55b6ec70$@com> From: Jonathan Ellis Date: Wed, 10 Mar 2010 10:00:56 -0600 Message-ID: Subject: Re: Bad read performances: 'few rows of many columns' vs 'many rows of few columns' To: cassandra-user@incubator.apache.org Content-Type: text/plain; charset=ISO-8859-1 For the record, I note that "no row cache" is the default on user-defined CFs; we include it in the sample configuration file as an example only. On Wed, Mar 10, 2010 at 9:58 AM, Sylvain Lebresne wrote: >> So did you disable the row cache entirely? > > Yes (getting back reasonable performances). > >>> From: Sylvain Lebresne >>> >>> Well, I've found the reason. >>> The default cassandra configuration use a 10% row cache. >>> And the row cache reads all the row each time. So it was indeed reading >>> the >>> full row each time even though the request was asking for only one >>> column. >>> >>> Sylvain >> >> >> >