Return-Path: 
 <user-return-8859-apmail-cassandra-user-archive=cassandra.apache.org@cassandra.apache.org>
Delivered-To: apmail-cassandra-user-archive@www.apache.org
Received: (qmail 59345 invoked from network); 30 Aug 2010 13:11:07 -0000
Received: from unknown (HELO mail.apache.org) (140.211.11.3)
  by 140.211.11.9 with SMTP; 30 Aug 2010 13:11:07 -0000
Received: (qmail 23836 invoked by uid 500); 30 Aug 2010 13:11:05 -0000
Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org
Received: (qmail 22975 invoked by uid 500); 30 Aug 2010 13:11:01 -0000
Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
List-Help: <mailto:user-help@cassandra.apache.org>
List-Unsubscribe: <mailto:user-unsubscribe@cassandra.apache.org>
List-Post: <mailto:user@cassandra.apache.org>
List-Id: <user.cassandra.apache.org>
Reply-To: user@cassandra.apache.org
Delivered-To: mailing list user@cassandra.apache.org
Received: (qmail 22943 invoked by uid 99); 30 Aug 2010 13:11:00 -0000
Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136)
    by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 30 Aug 2010 13:11:00 +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 (athena.apache.org: domain of jbellis@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; Mon, 30 Aug 2010 13:10:55 +0000
Received: by vws10 with SMTP id 10so5485918vws.31
        for <multiple recipients>; Mon, 30 Aug 2010 06:10:33 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=gamma;
        h=domainkey-signature:received:mime-version:received:in-reply-to
         :references:from:date:message-id:subject:to:content-type
         :content-transfer-encoding;
        bh=sfvc+e8VXM0QG/XuE5axKK8BrGFLOUubVYvEJRvkF9U=;
        b=d12dDethYWyXm3qNnJDxmzOHv5zz3FNxvkxWOqHo1Eoc1cyyIgKro+vcNUgn/ZDenf
         bL6+jnLsbMK1ne9oh+ka2o1Dd+dUVug8U2qYnvL9AI/TSp2c4cEFdROYvpy0OBXZo1k9
         MMPhg3AtODYTN9Zzzv8F8RIWrRklgW1/UQwX0=
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:content-transfer-encoding;
        b=MHBZLmjznKaEaRYXj/wlkFbt3wR24lveNlD/7TAkDuhRlUFPBSaQSZYs/+8vSe4wVo
         iUI43x/JargOvkWmMrVr51FvZcxvhYRe7RpfhXkInHM5VP4odr9kwzcJMI612PDWqSWq
         vOmT6x9A6HjuZc1I2Wcx1Kt+HpGpKceUB51fw=
Received: by 10.220.122.31 with SMTP id j31mr2776719vcr.271.1283173832339;
 Mon, 30 Aug 2010 06:10:32 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.220.201.129 with HTTP; Mon, 30 Aug 2010 06:10:10 -0700 (PDT)
In-Reply-To: <AANLkTi=-x7DrgE4JBg_eq34ze48ow8ygzOJn_q2eoxHN@mail.gmail.com>
References: <AANLkTi=-x7DrgE4JBg_eq34ze48ow8ygzOJn_q2eoxHN@mail.gmail.com>
From: Jonathan Ellis <jbellis@gmail.com>
Date: Mon, 30 Aug 2010 08:10:10 -0500
Message-ID: <AANLkTimJx01uJboPQ2SZX-DKvZRfrML3xza6FWfS-vxM@mail.gmail.com>
Subject: Re: cassandra disk usage
To: user@cassandra.apache.org
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

column names are stored per cell

(moving to user@)

On Mon, Aug 30, 2010 at 6:58 AM, Terje Marthinussen
<tmarthinussen@gmail.com> wrote:
> Hi,
>
> Was just looking at a SSTable file after loading a dataset. The data load
> has no updates of data =A0but:
> - Columns can in some rare cases be added to existing super columns
> - SuperColumns will be added to the same key (but not overwriting existin=
g
> data). I batch these, but it is quite likely that there will be 2-3 updat=
es
> to a key.
>
> This is a random selected SSTable file from a much bigger dataset.
>
> The data is stored as date(super)/type(column)/value
> Date is a simple "20100811" type string.
> Value is a small integer, 2 digit on average
>
> If I run a simple strings on the SSTable and look for the data:
> value: 692Kbyte of data
> type: 4.01MByte of data
> date: 4.6MB of data
>
> In total: 9.4MByte
>
> The size of the .db file however, is 36.4MB...
>
> The expansion from the column headers are bad enough, but I can somehow
> accept that.
> The almost 4x expansion on top of that is a bit harder to justify...
>
> Anyone know already where this expansion comes from? Or I need to take a
> careful look at source (probably useful anyway :))
>
> Terje
>



--=20
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com