Return-Path: X-Original-To: apmail-hadoop-user-archive@minotaur.apache.org Delivered-To: apmail-hadoop-user-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 5B4BA11ECE for ; Thu, 19 Jun 2014 10:07:06 +0000 (UTC) Received: (qmail 67715 invoked by uid 500); 19 Jun 2014 10:07:02 -0000 Delivered-To: apmail-hadoop-user-archive@hadoop.apache.org Received: (qmail 67603 invoked by uid 500); 19 Jun 2014 10:07:02 -0000 Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hadoop.apache.org Delivered-To: mailing list user@hadoop.apache.org Received: (qmail 67593 invoked by uid 99); 19 Jun 2014 10:07:01 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 19 Jun 2014 10:07:01 +0000 X-ASF-Spam-Status: No, hits=2.2 required=5.0 tests=HTML_MESSAGE,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: local policy) Received: from [87.230.46.220] (HELO vwp3725.webpack.hosteurope.de) (87.230.46.220) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 19 Jun 2014 10:06:57 +0000 Received: from [92.245.190.43] (helo=[10.5.50.3]); authenticated by vwp3725.webpack.hosteurope.de running ExIM with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) id 1WxZEn-0000uW-Fe; Thu, 19 Jun 2014 12:06:34 +0200 From: Kai Voigt Content-Type: multipart/alternative; boundary="Apple-Mail=_29E7FCBA-A2E0-4D7C-9446-7FB3E4BE7826" Message-Id: <2156F436-3AFF-4CB7-8970-484379366471@123.org> Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.2\)) Subject: Re: Map reduce Query Date: Thu, 19 Jun 2014 12:06:31 +0200 References: To: user@hadoop.apache.org In-Reply-To: X-Mailer: Apple Mail (2.1878.2) X-bounce-key: webpack.hosteurope.de;k@123.org;1403172416;34c5ef22; X-Virus-Checked: Checked by ClamAV on apache.org --Apple-Mail=_29E7FCBA-A2E0-4D7C-9446-7FB3E4BE7826 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 That=92s exactly what MapReduce does. The input is processed by the = mapper function, and its output will be automatically sent into the = reducer function. Between mappers and reducers we have the automatic = shuffle phase which sends records with identical keys into one reducer = call. If you want to simply not modify the data through the map phase, just = don=92t specify the mapper class in your driver code. The identity = function will be used for the map phase in this case. Kai Am 19.06.2014 um 11:00 schrieb Shrivastava, Himnshu (GE Global Research, = Non-GE) : > Can we take input in a mapper function and in some way pass it to = reducer ? > =20 > Regards, Kai Voigt Am Germaniahafen 1 = k@123.org 24143 Kiel = +49 160 96683050 Germany = @KaiVoigt --Apple-Mail=_29E7FCBA-A2E0-4D7C-9446-7FB3E4BE7826 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 That=92s= exactly what MapReduce does. The input is processed by the mapper = function, and its output will be automatically sent into the reducer = function. Between mappers and reducers we have the automatic shuffle = phase which sends records with identical keys into one reducer = call.

If you want to simply not modify the data = through the map phase, just don=92t specify the mapper class in your = driver code. The identity function will be used for the map phase in = this case.

Kai

Am = 19.06.2014 um 11:00 schrieb Shrivastava, Himnshu (GE Global Research, = Non-GE) <Himnshu.Shrivastava@ge.com&= gt;:

Can we take input in = a mapper function and in some way pass it  to reducer = ?

 

Regards,


Kai = Voigt Am = Germaniahafen 1 k@123.org
= 24143 Kiel = +49 160 96683050
= Germany = @KaiVoigt

= --Apple-Mail=_29E7FCBA-A2E0-4D7C-9446-7FB3E4BE7826--