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From "Ilya Vishnevsky" <Ilya.Vishnev...@e-legion.com>
Subject RE: Global information in MapReduce
Date Mon, 19 Mar 2007 16:25:16 GMT

Thanks, that's a good idea. As I understand, file name will be passed
using set() or setObject() methods of JobConf. Am I right? But what if
I'll try to use JobConf to pass the whole list of words to the mapper?
Is it possible?

One way to do that is to store your words in a DFS file.
In the configure method of your mapper class, you can read the words in
the file and use them. You can use JobConf to pass the file name to the


> -----Original Message-----
> From: Ilya Vishnevsky [mailto:Ilya.Vishnevsky@e-legion.com]
> Sent: Monday, March 19, 2007 8:13 AM
> To: hadoop-user@lucene.apache.org
> Subject: Global information in MapReduce
> Hello! My question is about mapreduce. Is it possible to pass to the
> function some global information? For example I have a set of words
> a large set of documents. I want the map function to get each document
> as value and emit pairs (word-frequency) for each word in the set,
> "frequency" is frequency of this word in the document. To do this I
> map function to have access to the set of words each time it runs. Is
> possible to do that?

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