Return-Path: Delivered-To: apmail-hadoop-hbase-user-archive@minotaur.apache.org Received: (qmail 16298 invoked from network); 1 Sep 2009 20:52:25 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 1 Sep 2009 20:52:25 -0000 Received: (qmail 51159 invoked by uid 500); 1 Sep 2009 20:52:24 -0000 Delivered-To: apmail-hadoop-hbase-user-archive@hadoop.apache.org Received: (qmail 51080 invoked by uid 500); 1 Sep 2009 20:52:24 -0000 Mailing-List: contact hbase-user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: hbase-user@hadoop.apache.org Delivered-To: mailing list hbase-user@hadoop.apache.org Received: (qmail 51070 invoked by uid 99); 1 Sep 2009 20:52:24 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 01 Sep 2009 20:52:24 +0000 X-ASF-Spam-Status: No, hits=3.4 required=10.0 tests=HTML_MESSAGE,SPF_NEUTRAL X-Spam-Check-By: apache.org Received-SPF: neutral (athena.apache.org: local policy) Received: from [76.13.9.53] (HELO web65509.mail.ac4.yahoo.com) (76.13.9.53) by apache.org (qpsmtpd/0.29) with SMTP; Tue, 01 Sep 2009 20:52:14 +0000 Received: (qmail 20819 invoked by uid 60001); 1 Sep 2009 20:51:53 -0000 Message-ID: <121250.10533.qm@web65509.mail.ac4.yahoo.com> X-YMail-OSG: NA82GGYVM1kMhxmRXcR.iOBMxtv.Yg3Cv_t99xnmL__63OWVeRjtkW0_CePeGsH38Ngmrqv8dFyjVuqjAqTQTjy2SGK1uq82Ndz8K5x5oPo0CymEaJ_DIpW0peX8QcVcMml3yVYGTxQ.lFi4BTmGkLydJs.o46ApzXlh.OXkrW_8q7Z.KJb04W_K5am5yAocvGC8Xw8Leo_Wd4tkY1E7SMaXGLh1fv_DlSI6LSoryBXNn8ZmBlRhnpwPy9g1YvIyGFi9CzXrT3jQ4NxuxSgEO_eNBhieq.skLc6pni_A16DK9ljN.G7RJsG_Xjbsf5NymM0NZqwq6C.Tkhqg_KsY3WYsDgew3iGQSZ2.KJBoPHGFs1.Qdd.Td6oNNGJuZLP2gF8idw-- Received: from [69.111.72.178] by web65509.mail.ac4.yahoo.com via HTTP; Tue, 01 Sep 2009 13:51:53 PDT X-RocketYMMF: apurtell X-Mailer: YahooMailRC/1358.27 YahooMailWebService/0.7.338.2 References: <710ef8220909011145n66579315od6b68c00ba13f063@mail.gmail.com> <7c962aed0909011223j466f73c6l7c75eddfc4cf2025@mail.gmail.com> Date: Tue, 1 Sep 2009 13:51:53 -0700 (PDT) From: Andrew Purtell Subject: Re: Cassandra vs HBase To: hbase-user@hadoop.apache.org In-Reply-To: <7c962aed0909011223j466f73c6l7c75eddfc4cf2025@mail.gmail.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1952114859-1251838313=:10533" X-Virus-Checked: Checked by ClamAV on apache.org --0-1952114859-1251838313=:10533 Content-Type: text/plain; charset=us-ascii >From my point of view the biggest difference between the two systems is the following: Cassandra can always accept writes. It uses its own local storage (no dependence on HDFS or anything like that) and P2P data replication. In contrast, HBase depends on HDFS so is unavailable if the filesystem has a problem, and furthermore if regions are in transition due to node failure or load balancing then writes to the affected region are temporarily blocked until it is available again. In exchange for always accepting writes, depending on what fails where and when, reads in Cassandra may only retrieve stale data, or the reads of some clients can be inconsistent with reads of others. Eventually all reads will return the last written value. In contrast, HBase and Hypertable and Google's implementation are strongly consistent systems. A read always returns the last written value. In the proposed HBase replication system (HBASE-1295), each peer cluster is strongly consistent but edits will be asynchronously propagated between them -- we call this regional consistency. - Andy On Tue, Sep 1, 2009 at 11:45 AM, charles du wrote: > Hi: > > Does anyone have experience with both Cassandra and HBase? To me, they > target at a similar problem. I am wondering what are main differences > between these two, like reliablity/performance/features? > > Thanks. > > -- > tp > --0-1952114859-1251838313=:10533--