Hadoop in Action

Chapter 7. Cookbook

This chapter covers

• Passing custom parameters to tasks
• Retrieving task-specific information
• Creating multiple outputs
• Interfacing with relational databases
• Making output globally sorted

This book so far has covered the core techniques for making a MapReduce program. Hadoop is a big framework that supports many more functionalities than those core techniques. In this age of Bing and Google, you can look up specialized MapReduce techniques rather easily, and we don’t try to be an encyclopedic reference. In our own usage and from our discussion with other Hadoop users, we’ve found a number of techniques generally useful, techniques such as being able to take a standard relational database as input or output to a MapReduce ...