Map Reduce


WordCount2 Output
Hadoop provided some predefined Mapper and Reducer classes in its Java API and these will be helpful in writing simple or default mapreduce jobs. A few among the entire list of predefined mapper and reducer classes are provided below. Identity Mapper Identity Mapper is the default Mapper class provided by […]

Predefined Mapper and Reducer Classes


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Mapreduce Job Flow Through YARN Implementation This post is to describe the mapreduce job flow – behind the scenes, when a job is submit to hadoop through submit() or waitForCompletion() method on Job object. This Mapreduce job flow is explained with the help of Word Count mapreduce program described in […]

MapReduce Job Flow


hadoop jar wordcount2 1
In this post, we are going to review the building blocks & programming model of example mapreduce program word count run in previous post in this Mapreduce Category. We will not go too deep into code, our focus will be mainly on structure of the mapreduce program written in java […]

MapReduce Programming Model



MR File exist exception 2
For testing YARN/Map Reduce Installation, we can run example mapreduce program (word count job) from the hadoop download directory. Hadoop release will contain map reduce examples in ¬†share/hadoop/mapreduce/hadoop-mapreduce-examples-x.y.z.jar file. In this demonstration, we will consider wordcount¬†mapreduce program from the above jar to test the counts of each word in a […]

Run Example MapReduce Program