Return-Path: Delivered-To: apmail-hadoop-hbase-user-archive@minotaur.apache.org Received: (qmail 67858 invoked from network); 10 Jun 2009 04:44:47 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 10 Jun 2009 04:44:47 -0000 Received: (qmail 90240 invoked by uid 500); 10 Jun 2009 04:44:58 -0000 Delivered-To: apmail-hadoop-hbase-user-archive@hadoop.apache.org Received: (qmail 90181 invoked by uid 500); 10 Jun 2009 04:44:58 -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 90171 invoked by uid 99); 10 Jun 2009 04:44:58 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 10 Jun 2009 04:44:57 +0000 X-ASF-Spam-Status: No, hits=2.2 required=10.0 tests=HTML_MESSAGE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of wqt.work@gmail.com designates 209.85.219.219 as permitted sender) Received: from [209.85.219.219] (HELO mail-ew0-f219.google.com) (209.85.219.219) by apache.org (qpsmtpd/0.29) with ESMTP; Wed, 10 Jun 2009 04:44:48 +0000 Received: by ewy19 with SMTP id 19so198537ewy.29 for ; Tue, 09 Jun 2009 21:44:28 -0700 (PDT) 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=vqyfrTS6jktfGtBY4PjA9j91yA8mhYNdE+0ePb52sks=; b=fxPF6eBlTqm+gxkI6gKTnPWV4HQWH9odluGY/2yvekRr+zuRqMT5oSoiH/fvzuFJ3M x8Gyt7H9Xvydbg3cW5bnIXM8dMrKYZ+DkYlU3QY/tdrkZdgSBROzQXLNTuEN8Bmqf6nz lIeMf+bje7cQK29oWmEy2iDVju3Z+MvT6FBrE= 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=P2A6pihFmO+OxWeOmt6U/dnDSv3IsTXLnXGVLGhK25BqFwFbbrppFfY7xEwc26GhdK AscieTOBXUn7QIN6j924SJgMz0zqcnJ3RwW/8wgTwF9RZpNDtUfJx7fCjFrs310rB97G Lfqty2fknLbSYTAyPWLmtnD8SxdKc2IblNsq0= MIME-Version: 1.0 Received: by 10.210.79.3 with SMTP id c3mr3279080ebb.24.1244609067690; Tue, 09 Jun 2009 21:44:27 -0700 (PDT) In-Reply-To: <78568af10906091935q16c0e27cr781a5f121ce31782@mail.gmail.com> References: <21224f560906091410x2a8f98e9v8ee7d72e90026749@mail.gmail.com> <5b9fff10906091431n2b18d1ddp53e8c96c501fb49b@mail.gmail.com> <21224f560906091923kf9da008y28f741a4720ad636@mail.gmail.com> <78568af10906091933x4581ec8ewd704e75ce07170e4@mail.gmail.com> <78568af10906091935q16c0e27cr781a5f121ce31782@mail.gmail.com> From: Ric Wang Date: Tue, 9 Jun 2009 23:44:05 -0500 Message-ID: <21224f560906092144o703e9292o1587a74cceae2a3@mail.gmail.com> Subject: Re: scanner on a given column: whole table scan or just the rows that have values To: hbase-user@hadoop.apache.org Content-Type: multipart/alternative; boundary=0015174c46165d2b1a046bf72132 X-Virus-Checked: Checked by ClamAV on apache.org --0015174c46165d2b1a046bf72132 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, Thanks. But if it is still scanning EVERY row in the entire table, how does HBase achieve better scan performance, compared to a row-based database? Thanks, Ric On Tue, Jun 9, 2009 at 9:35 PM, Ryan Rawson wrote: > Without the use of indexes, there is no easy way to get the info without > touching every row. > > So yes you'll be scanning every row. But hbase has good bulk scan perf. > > On Jun 9, 2009 7:24 PM, "Ric Wang" wrote: > > How does the scanner know how to get ONLY the "relevant" rows, without a > whole table scan? > > Thanks! > Ric > > On Tue, Jun 9, 2009 at 4:31 PM, Naveen Koorakula > wrote: > > The scanner only s... > -- > > Ric Wang wqt.work@gmail.com > -- Ric Wang wqt.work@gmail.com --0015174c46165d2b1a046bf72132--