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MapReduce >> mail # user >> Multiple files as input to a mapreduce job

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RE: Multiple files as input to a mapreduce job
Hi Shreya,


The functionality expected by you achieved by Hive (Internally by Mapred).

May be you can take look in Hive Join logics or can use Hive directly.

You can look into org.apache.hadoop.mapred.lib.CombineFileInputFormat<K,V>
and related classes for more details.

Subroto Sanyal


Sent: Friday, September 09, 2011 11:54 AM
Subject: Multiple files as input to a mapreduce job




The following is the scenario I have:


I have a java program that reads multiple files from the disk.

*         There are 3 files (A,B,C) that are read and populated into 3
collections (arraylist).

*         There are 2 files input1 and input2 that act as input to my

*         I search a keyword in file input1 and find the ID corresponding to
the matching entries.

*         This ID is used in file input2 to fetch the entries  corresponding
to it.

There has to be a join between input1 and input2


I want to convert it into a map reduce program, is that possible?

How can we read multiple input files in the mapper, can we read files from
the disk.

Please Advice...





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