Hadoop MapReduce v2 Cookbook - Second Edition

Joining two datasets using Pig

This recipe explains how to join two datasets using Pig. We will use the BookCrossing dataset for this recipe. This recipe will use Pig to join the Books dataset with the Book-Ratings dataset and find the distribution of high ratings (with rating>3) with respect to authors.

How to do it...

This section describes how to use a Pig Latin script to find author's review rating distribution by joining the Books dataset with the Ratings dataset:

1. Extract the BookCrossing sample dataset (chapter6-bookcrossing-data.tar.gz) from the chapter6 folder of the code repository.
2. Create a directory in HDFS and copy the BookCrossing Books dataset and the Book-Ratings dataset to that directory, as follows:

   $ hdfs dfs –mkdir book-crossing ...