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MapReduce >> mail # user >> RE: a question on MapReduce


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RE: a question on MapReduce
Hehe,... good to know. Thanks.
From: Mohammad Tariq [mailto:[EMAIL PROTECTED]]
Sent: Monday, November 19, 2012 9:50 AM
To: [EMAIL PROTECTED]
Subject: Re: a question on MapReduce

Hello Andy,

  Reduce phase starts only once the Map phase is 100% complete. The reduce progress you see actually signifies other intermediate processes like shuffle and sort. Don't get confused with it like I did initially :)

Regards,
    Mohammad Tariq
On Mon, Nov 19, 2012 at 8:07 PM, Kartashov, Andy <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Guys,

Sometimes when I run my MR job I see that Reduce tasks kick in as early as when Map task reached only about 20%. How can the MR be possibly so sure and start running Reduce at this point? What if a Mapper  produce more keys that Reduce function already finished with?

Andy Kartashov
MPAC
IT Architecture, Co-op
1340 Pickering Parkway, Pickering, L1V 0C4
* Phone : (905) 837 6269
* Mobile: (416) 722 1787
[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>

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NOTICE: This e-mail message and any attachments are confidential, subject to copyright and may be privileged. Any unauthorized use, copying or disclosure is prohibited. If you are not the intended recipient, please delete and contact the sender immediately. Please consider the environment before printing this e-mail. AVIS : le présent courriel et toute pièce jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur et peuvent être couverts par le secret professionnel. Toute utilisation, copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le destinataire prévu de ce courriel, supprimez-le et contactez immédiatement l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent courriel
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB