Return-Path: X-Original-To: apmail-hbase-user-archive@www.apache.org Delivered-To: apmail-hbase-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id E112A10668 for ; Thu, 25 Apr 2013 21:35:02 +0000 (UTC) Received: (qmail 55072 invoked by uid 500); 25 Apr 2013 21:35:00 -0000 Delivered-To: apmail-hbase-user-archive@hbase.apache.org Received: (qmail 54911 invoked by uid 500); 25 Apr 2013 21:35:00 -0000 Mailing-List: contact user-help@hbase.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hbase.apache.org Delivered-To: mailing list user@hbase.apache.org Received: (qmail 54903 invoked by uid 99); 25 Apr 2013 21:35:00 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 25 Apr 2013 21:35:00 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of jdcryans@gmail.com designates 209.85.212.42 as permitted sender) Received: from [209.85.212.42] (HELO mail-vb0-f42.google.com) (209.85.212.42) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 25 Apr 2013 21:34:53 +0000 Received: by mail-vb0-f42.google.com with SMTP id p12so3133881vbe.29 for ; Thu, 25 Apr 2013 14:34:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; bh=M+84FGTkelTnGMA1tSGSNBlQchhrkOhpnw2f6+qNEpI=; b=vj3gEDddgCKb6y9jQL8V+dqxVVOuVRkdNUBtTvcIHk5wb2XmER4dYKtw/vmGHaBJFM zqV7BrCB9b++Im56JArmvlRwyJf3CT/GyTgtLf84RZyc1hlgLIEupChJrIgywVk02A16 O6osIhBsP6Z4/ziwME70xC4dGgtuhCSJwlwfbqG/nxHd53CKbAzVWdwgmRcgIeeuVDQM Dt/zsXv59iDxyKAL291u8A2a7l9G3XPR1kwVdAhgAuigSDgS/BKhY5AYIRUo/kkb3Ser EhQ0ttYEPHOK9KXmUfAthb2wKiyOqIrNAmtKY5nkR/hNS3pCJygchgHzspfSXPfLpC6/ lcVw== MIME-Version: 1.0 X-Received: by 10.52.111.100 with SMTP id ih4mr23390575vdb.98.1366925673113; Thu, 25 Apr 2013 14:34:33 -0700 (PDT) Sender: jdcryans@gmail.com Received: by 10.220.113.206 with HTTP; Thu, 25 Apr 2013 14:34:32 -0700 (PDT) In-Reply-To: <1A3C673C-A26F-4485-B60C-5384FCFED0E5@sproutsocial.com> References: <1A3C673C-A26F-4485-B60C-5384FCFED0E5@sproutsocial.com> Date: Thu, 25 Apr 2013 14:34:32 -0700 X-Google-Sender-Auth: U882vGAAKBHRDNryOYT2z_oy7Z8 Message-ID: Subject: Re: writing and reading from a region at once From: Jean-Daniel Cryans To: "user@hbase.apache.org" Content-Type: multipart/alternative; boundary=bcaec54862fa2e309504db362f93 X-Virus-Checked: Checked by ClamAV on apache.org --bcaec54862fa2e309504db362f93 Content-Type: text/plain; charset=ISO-8859-1 Inline. J-D On Thu, Apr 25, 2013 at 1:09 PM, Aaron Zimmerman < azimmerman@sproutsocial.com> wrote: > Hi, > > If a region is being written to, and a scanner takes a lease out on the > region, what will happen to the writes? Is there a concept of "Transaction > Isolation Levels"? > There's MVCC, so reads can happen while someone else is writing. What you should expect from HBase is "read committed". > > I don't see errors in Puts while the tables are being scanned? But it > seems that I'm losing writes somewhere, is it possible the writes could > fail silently? > Is it temporary while you're scanning or there's really data missing at the end of the day? The former might happen on some older HBase versions while the latter should never happen unless you lower the durability level yourself and have machine failures. J-D --bcaec54862fa2e309504db362f93--