Hadoop Beginner's Guide

Summary

This chapter has used three case studies to highlight some more advanced aspects of Hadoop and its broader ecosystem. In particular, we covered the nature of join-type problems and where they are seen, how reduce-side joins can be implemented with relative ease but with an efficiency penalty, and how to use optimizations to avoid full joins in the map-side by pushing data into the Distributed Cache.

We then learned how full map-side joins can be implemented, but require significant input data processing; how other tools such as Hive and Pig should be investigated if joins are a frequently encountered use case; and how to think about complex types like graphs and how they can be represented in a way that can be used in MapReduce.

We also ...