MapReduce and the secondary index
How MapReduce works
MapReduce is a two-phase paradigm for crunching large data sets in a distributed system. This video uses a basic example to explain how MapReduce works.
Use the secondary index
Ideal for routine queries, secondary indexes use MapReduce to build indexes over large amounts of data. The secondary index provides a way for you to query data in more ways than just a simple primary key lookup. This video shows you how to create a secondary index, and construct queries to access the secondary index through the API.
Advanced use of the secondary index
Move on from the basics of working with a secondary index to some more advanced techniques.
If you are interested in trying out some tutorials to get some hands-on experience working with a secondary index, try out the Use the Secondary Index tutorial on github.