From user-return-19417-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org Tue Aug 2 22:05:56 2011 Return-Path: X-Original-To: apmail-cassandra-user-archive@www.apache.org Delivered-To: apmail-cassandra-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 3DBFC64D5 for ; Tue, 2 Aug 2011 22:05:56 +0000 (UTC) Received: (qmail 75606 invoked by uid 500); 2 Aug 2011 22:05:54 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 75555 invoked by uid 500); 2 Aug 2011 22:05:53 -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 75547 invoked by uid 99); 2 Aug 2011 22:05:53 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 02 Aug 2011 22:05:53 +0000 X-ASF-Spam-Status: No, hits=-0.0 required=5.0 tests=SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: local policy) Received: from [38.102.63.180] (HELO smtp-1.01.com) (38.102.63.180) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 02 Aug 2011 22:05:44 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp-1.01.com (Postfix) with ESMTP id 480953643CE for ; Tue, 2 Aug 2011 17:05:24 -0500 (CDT) Received: from smtp-1.01.com ([127.0.0.1]) by localhost (smtp-1.01.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id g1PRiZBL5Aff for ; Tue, 2 Aug 2011 17:05:24 -0500 (CDT) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp-1.01.com (Postfix) with ESMTP id 24E8B3643D1 for ; Tue, 2 Aug 2011 17:05:24 -0500 (CDT) Received: from mail-1.01.com (mail-1.01.com [38.102.63.171]) by smtp-1.01.com (Postfix) with ESMTP id 0EA3E3643CE for ; Tue, 2 Aug 2011 17:05:24 -0500 (CDT) Date: Tue, 2 Aug 2011 17:05:23 -0500 (CDT) From: Konstantin Naryshkin To: user@cassandra.apache.org Message-ID: <428603559.11060.1312322723898.JavaMail.root@mail-1.01.com> In-Reply-To: Subject: Re: Question about eventually consistent in Cassandra MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [96.237.179.12] X-Mailer: Zimbra 7.1.1_GA_3213 (ZimbraWebClient - FF3.0 (Linux)/7.1.1_GA_3196) I believe that what would happen is that whichever data center has the late= r clock will win. Every modification you make gets a time stamp (generally = set by your client to the current time, if you are using one). I believe th= at whatever modification happened with the last time stamp is canonical. Wh= at would happen if you make conflicting changes with the exact same time st= amp? No idea. ----- Original Message ----- From: "Eldad Yamin" To: user@cassandra.apache.org Sent: Tuesday, August 2, 2011 8:58:23 PM Subject: Question about eventually consistent in Cassandra Hi, Let=E2=80=99s say that I have 2 datacenters, a key is changed on both of my datacenters in the exact same time (even in 1-2 seconds diff). Datacenter #1 add column "abc" with value X Datacenter #2 add column "abc" with value Y. What is the result of that situation? Is there any different if the changes will be made withing the same data center? Thanks! Eldad Yamin