Return-Path: 
 <mapreduce-user-return-1324-apmail-hadoop-mapreduce-user-archive=hadoop.apache.org@hadoop.apache.org>
Delivered-To: apmail-hadoop-mapreduce-user-archive@minotaur.apache.org
Received: (qmail 44968 invoked from network); 8 Nov 2010 11:32:15 -0000
Received: from unknown (HELO mail.apache.org) (140.211.11.3)
  by 140.211.11.9 with SMTP; 8 Nov 2010 11:32:15 -0000
Received: (qmail 16255 invoked by uid 500); 8 Nov 2010 11:32:46 -0000
Delivered-To: apmail-hadoop-mapreduce-user-archive@hadoop.apache.org
Received: (qmail 15889 invoked by uid 500); 8 Nov 2010 11:32:44 -0000
Mailing-List: contact mapreduce-user-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
List-Help: <mailto:mapreduce-user-help@hadoop.apache.org>
List-Unsubscribe: <mailto:mapreduce-user-unsubscribe@hadoop.apache.org>
List-Post: <mailto:mapreduce-user@hadoop.apache.org>
List-Id: <mapreduce-user.hadoop.apache.org>
Reply-To: mapreduce-user@hadoop.apache.org
Delivered-To: mailing list mapreduce-user@hadoop.apache.org
Received: (qmail 15881 invoked by uid 99); 8 Nov 2010 11:32:43 -0000
Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230)
    by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 08 Nov 2010 11:32:43 +0000
X-ASF-Spam-Status: No, hits=2.9 required=10.0
	tests=HTML_MESSAGE,RCVD_IN_DNSWL_NONE,SPF_NEUTRAL
X-Spam-Check-By: apache.org
Received-SPF: neutral (nike.apache.org: local policy)
Received: from [209.85.212.48] (HELO mail-vw0-f48.google.com) (209.85.212.48)
    by apache.org (qpsmtpd/0.29) with ESMTP; Mon, 08 Nov 2010 11:32:33 +0000
Received: by vws5 with SMTP id 5so1762615vws.35
        for <mapreduce-user@hadoop.apache.org>;
 Mon, 08 Nov 2010 03:32:12 -0800 (PST)
MIME-Version: 1.0
Received: by 10.224.219.10 with SMTP id hs10mr185174qab.121.1289215931888;
 Mon, 08 Nov 2010 03:32:11 -0800 (PST)
Sender: niels@basj.es
Received: by 10.229.189.133 with HTTP; Mon, 8 Nov 2010 03:32:11 -0800 (PST)
X-Originating-IP: [212.121.118.65]
In-Reply-To: <AANLkTim6gE-0DX5CJ0CC1iSsBmoXrF4QzRwqYaMBiueJ@mail.gmail.com>
References: <AANLkTim6gE-0DX5CJ0CC1iSsBmoXrF4QzRwqYaMBiueJ@mail.gmail.com>
Date: Mon, 8 Nov 2010 12:32:11 +0100
X-Google-Sender-Auth: kmdj1evBrQUqYtN5KjrO_CUWuNo
Message-ID: <AANLkTimM9KCzh6G_pWa7GLU0z1kz1CtsO84vy4Q9+v_P@mail.gmail.com>
Subject: Re: Predicting how many values will I see in a call to reduce?
From: Niels Basjes <Niels@basjes.nl>
To: mapreduce-user@hadoop.apache.org
Content-Type: multipart/alternative; boundary=20cf3010edd5a8b653049488f9bd
X-Virus-Checked: Checked by ClamAV on apache.org

--20cf3010edd5a8b653049488f9bd
Content-Type: text/plain; charset=ISO-8859-1

Hi,

2010/11/7 Anthony Urso <anthony.urso@gmail.com>

> Is there any way to know how many values I will see in a call to
> reduce without first counting through them all with the iterator?
>
> Under 0.21? 0.20? 0.19?
>

I've looked for an answer to the same question a while ago and came to the
conclusion that you can't.
The main limit is that the Iterator does not have a "size" or "length"
method.

-- 
Met vriendelijke groeten,

Niels Basjes

--20cf3010edd5a8b653049488f9bd
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

Hi,<br><br><div class=3D"gmail_quote">2010/11/7 Anthony Urso <span dir=3D"l=
tr">&lt;<a href=3D"mailto:anthony.urso@gmail.com">anthony.urso@gmail.com</a=
>&gt;</span><br><blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt =
0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Is there any way to know how many values I will see in a call to<br>
reduce without first counting through them all with the iterator?<br>
<br>
Under 0.21? 0.20? 0.19?<br></blockquote><div><br>I&#39;ve looked for an ans=
wer to the same question a while ago and came to the conclusion that you ca=
n&#39;t.<br>The main limit is that the Iterator does not have a &quot;size&=
quot; or &quot;length&quot; method.<br>
</div></div><br>-- <br>Met vriendelijke groeten,<br><br>Niels Basjes<br>

--20cf3010edd5a8b653049488f9bd--