Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 42483 invoked from network); 11 Aug 2010 04:41:47 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 11 Aug 2010 04:41:47 -0000 Received: (qmail 84393 invoked by uid 500); 11 Aug 2010 04:41:46 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 84175 invoked by uid 500); 11 Aug 2010 04:41:43 -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 84167 invoked by uid 99); 11 Aug 2010 04:41:43 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 11 Aug 2010 04:41:43 +0000 X-ASF-Spam-Status: No, hits=-0.0 required=10.0 tests=RCVD_IN_DNSWL_NONE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of rcoli@digg.com designates 209.85.216.179 as permitted sender) Received: from [209.85.216.179] (HELO mail-qy0-f179.google.com) (209.85.216.179) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 11 Aug 2010 04:41:35 +0000 Received: by qyk8 with SMTP id 8so10356744qyk.10 for ; Tue, 10 Aug 2010 21:41:14 -0700 (PDT) Received: by 10.224.105.199 with SMTP id u7mr10279800qao.131.1281501672563; Tue, 10 Aug 2010 21:41:12 -0700 (PDT) Received: from rcolis-MacBook-Pro.local (c-98-210-205-15.hsd1.ca.comcast.net [98.210.205.15]) by mx.google.com with ESMTPS id q8sm6375893qcs.36.2010.08.10.21.41.10 (version=SSLv3 cipher=RC4-MD5); Tue, 10 Aug 2010 21:41:11 -0700 (PDT) Message-ID: <4C6229E5.4090409@digg.com> Date: Tue, 10 Aug 2010 21:41:09 -0700 From: Robert Coli User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: user@cassandra.apache.org Subject: Re: explanation of generated files and ops References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 8/9/10 9:00 PM, S Ahmed wrote: > What exactly is stored in the "....-Filter.db" files? Oh, didn't see this line. http://wiki.apache.org/cassandra/ArchitectureOverview " Bloom filter (all keys in data file). A Bloom filter, is a space-efficient probabilistic data structure that is used to test whether an element is a member of a set. False positives are possible, but false negatives are not. Cassandra uses bloom filters to save IO when performing a key lookup: each SSTable has a bloom filter associated with it that Cassandra checks before doing any disk seeks, making queries for keys that don't exist almost free. " =Rob