Return-Path: 
 <general-return-749-apmail-hadoop-general-archive=hadoop.apache.org@hadoop.apache.org>
Delivered-To: apmail-hadoop-general-archive@minotaur.apache.org
Received: (qmail 57253 invoked from network); 17 Nov 2009 04:11:24 -0000
Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3)
  by minotaur.apache.org with SMTP; 17 Nov 2009 04:11:24 -0000
Received: (qmail 62437 invoked by uid 500); 17 Nov 2009 04:11:23 -0000
Delivered-To: apmail-hadoop-general-archive@hadoop.apache.org
Received: (qmail 62329 invoked by uid 500); 17 Nov 2009 04:11:21 -0000
Mailing-List: contact general-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
List-Help: <mailto:general-help@hadoop.apache.org>
List-Unsubscribe: <mailto:general-unsubscribe@hadoop.apache.org>
List-Post: <mailto:general@hadoop.apache.org>
List-Id: <general.hadoop.apache.org>
Reply-To: general@hadoop.apache.org
Delivered-To: mailing list general@hadoop.apache.org
Received: (qmail 62319 invoked by uid 99); 17 Nov 2009 04:11:21 -0000
Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136)
    by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 17 Nov 2009 04:11:21 +0000
X-ASF-Spam-Status: No, hits=-2.4 required=5.0
	tests=AWL,BAYES_00,HTML_MESSAGE
X-Spam-Check-By: apache.org
Received-SPF: pass (athena.apache.org: domain of hkumar.arora@gmail.com
 designates 209.85.223.188 as permitted sender)
Received: from [209.85.223.188] (HELO mail-iw0-f188.google.com)
 (209.85.223.188)
    by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 17 Nov 2009 04:11:19 +0000
Received: by iwn26 with SMTP id 26so4925518iwn.5
        for <general@hadoop.apache.org>; Mon, 16 Nov 2009 20:10:58 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=gamma;
        h=domainkey-signature:mime-version:received:in-reply-to:references
         :date:message-id:subject:from:to:content-type;
        bh=FUME7HjkGUZtAnSh/GSypixY2+01H1yyEXXrGAtbFFY=;
        b=Ik3lfkGokZ47c7uvA/CRftYdiLC85niarf2XtSbuwWtGUFNjzfbsEdNcp2AAnbvHz9
         xtyfVFTrLIdigKCkackOFKDMfRpoMxyIFY+o7Z/m7DztQx6sTFUs9qxsNCNDxxL9Oi8C
         tzW+bwVi/yV8H9nli04hB4b+jd5eUHCkA3IGc=
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;
        b=J0WQbkDG1SF4FvdySmEvzQNQ/4RViuSo5d7ItqOu2kDxjiFoH7nNJJb2jHBxWIsZ0J
         04I4aoQyjk+uUUwkgmHHJ88JwpTeiOQ3bSqFK8RUjWzAQeAvsol9W8xQOOVFvwe1beLO
         HKa76nLvz547hvjcQcgdf2Azt8pUyFKUw5tQQ=
MIME-Version: 1.0
Received: by 10.231.158.205 with SMTP id g13mr960199ibx.30.1258431058069;
 Mon,
	16 Nov 2009 20:10:58 -0800 (PST)
In-Reply-To: <5f7f740b0911161947h5e001e15q9a15816f972aa08e@mail.gmail.com>
References: <1eabbac30911161143t4102be0brd0555eed21dd8572@mail.gmail.com>
	 <5f7f740b0911161947h5e001e15q9a15816f972aa08e@mail.gmail.com>
Date: Tue, 17 Nov 2009 13:10:58 +0900
Message-ID: <e497591c0911162010sbb6bd32g59aafcb8019bceda@mail.gmail.com>
Subject: Re: Values returned by Map to Reducer
From: Harshit Kumar <hkumar.arora@gmail.com>
To: general@hadoop.apache.org
Content-Type: multipart/alternative; boundary=00504501416d30c7680478895009

--00504501416d30c7680478895009
Content-Type: text/plain; charset=UTF-8

Oh Yes, you are right, i replied to this mail, saying yes. However, that yes
was for the keys which are sorted.
sorry for the confusion.


H. Kumar
Phone(Mobile): +82-10-2892-9663
Phone(Office): +82-31-
skype: harshit900
Blog: http://harshitkumar.wordpress.com
Website: http:/kumarharmuscat.tripod.com


2009/11/17 Owen O'Malley <owen.omalley@gmail.com>

> On Mon, Nov 16, 2009 at 11:43 AM, Something Something <
> mailinglists19@gmail.com> wrote:
>
> > Does Hadoop Mapreduce guarantee that the *values* returned by Mapper to
> the
> > Reducer are sorted?  Can I safely assume that?  Would it always be true -
> > at
> > least for 'Text' type?
> >
> > public void reduce(Text key, *Iterable<Text> values*, Context context
> >
>
> No, the values will *not* be sorted. In fact, it will be non-deterministic
> between multiple runs of the job with the same input. The keys will always
> be sorted. If you want the values to be sorted, you need to take additional
> steps. Please look at the SecondarySort example. It shows exactly how to
> get
> the values sorted in the order you desire.
>
> -- Owen
>

--00504501416d30c7680478895009--