Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 7385 invoked from network); 23 Apr 2010 17:15:39 -0000 Received: from unknown (HELO mail.apache.org) (140.211.11.3) by 140.211.11.9 with SMTP; 23 Apr 2010 17:15:39 -0000 Received: (qmail 83319 invoked by uid 500); 23 Apr 2010 17:08:18 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 83298 invoked by uid 500); 23 Apr 2010 17:08:18 -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 83290 invoked by uid 99); 23 Apr 2010 17:08:18 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 23 Apr 2010 17:08:18 +0000 X-ASF-Spam-Status: No, hits=0.0 required=10.0 tests=FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS,T_TO_NO_BRKTS_FREEMAIL X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of tsuraan@gmail.com designates 209.85.212.44 as permitted sender) Received: from [209.85.212.44] (HELO mail-vw0-f44.google.com) (209.85.212.44) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 23 Apr 2010 17:08:10 +0000 Received: by vws1 with SMTP id 1so954958vws.31 for ; Fri, 23 Apr 2010 10:07:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=AzFxZ1qPPv3l9SmWt/k8c1TduLDw3Zv8o2ZoWLFt95Y=; b=wdc67T4jK2Am6zvAGm9U6b4YQmNjEMwlk6Bjv9/2c6FxsOy8lJWTp7yOACbbgoAUaS EY9pZoDJ3U3gzJAgkTyiVEn7j9GkXeVasSTTIGC2KPz9VOa9u321aest6bkn6MZnnNiD Jyf0+RdKL36yeF0R8183NB+hWcw9g68Ug+aNs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=xg0RPp4vvILK6rpz8SMcf7S+Oj4H5UieV9W8GrHnoBWsJ6WR4nMakbQCqOXeuTyM13 3xOXfKfXsKuVp+h8ySiMxFPItf/FvGiwPLa5ALid/5ThVybf69NBpzMU1XKzGMGKfHC/ MrlJiWjkWWxLauWsod9kw94fUK+7KAIrOv7ZI= MIME-Version: 1.0 Received: by 10.220.129.14 with SMTP id m14mr205986vcs.75.1272042469712; Fri, 23 Apr 2010 10:07:49 -0700 (PDT) Received: by 10.220.172.204 with HTTP; Fri, 23 Apr 2010 10:07:49 -0700 (PDT) In-Reply-To: References: Date: Fri, 23 Apr 2010 12:07:49 -0500 Message-ID: Subject: Re: Concurrent SuperColumn update question From: tsuraan To: user@cassandra.apache.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Virus-Checked: Checked by ClamAV on apache.org > On Thu, Apr 22, 2010 at 11:34 AM, tsuraan wrote: >> Suppose I have a SuperColumn CF where one of the SuperColumns in each >> row is being treated as a list (e.g. keys only, values are just >> empty). =A0In this list, values will only ever be added; deletion never >> occurs. =A0If I have two processes simultaneously add values to this >> list (on different nodes, whatever), is that guaranteed to be safe >> from race conditions? > > As long as you use column names that do not collide, such as uuids. Ok, thanks. >> Also, in a scheme like this, is there a limit on the number of entries >> I can have in my "list"? =A0I know that compaction normally needs to >> read an entire row into RAM in order to compact it. =A0Does this also >> apply to SuperColumn columns? > > #3 here: http://wiki.apache.org/cassandra/CassandraLimitations Ouch, that's unfortunate. Thanks for pointing me to that one; I had somehow missed it, I guess.