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  • Book Overview & Buying Hadoop MapReduce v2 Cookbook - Second Edition: RAW
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Hadoop MapReduce v2 Cookbook - Second Edition: RAW

Hadoop MapReduce v2 Cookbook - Second Edition: RAW - Second Edition

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Hadoop MapReduce v2 Cookbook - Second Edition: RAW

Hadoop MapReduce v2 Cookbook - Second Edition: RAW

4.4 (7)

Overview of this book

If you are a Big Data enthusiast and wish to use Hadoop v2 to solve your problems, then this book is for you. This book is for Java programmers with little to moderate knowledge of Hadoop MapReduce. This is also a one-stop reference for developers and system admins who want to quickly get up to speed with using Hadoop v2. It would be helpful to have a basic knowledge of software development using Java and a basic working knowledge of Linux.
Table of Contents (12 chapters)
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11
Index

Simple analytics using MapReduce


Aggregate metrics such as mean, max, min, standard deviation, and so on, provide the basic overview of a dataset. You may perform these calculations, either for the whole dataset or to a subset or a sample of the dataset.

In this recipe, we will use Hadoop MapReduce to calculate the minimum, maximum, and average size of files served from a web server, by processing logs of the web server. The following figure shows the execution flow of this computation:

As shown in the figure, the Map function emits the size of the file as the value and the string msgSize as the key. We use a single Reduce task, and all the intermediate key-value pairs will be sent to that Reduce task. Then, the Reduce function calculates the aggregate values using the information emitted by the Map tasks.

Getting ready

This recipe assumes that you have a basic understanding of how the processing of Hadoop MapReduce works. If not, please follow the Writing a WordCount MapReduce application,...

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