A MapReduce pattern is a template for solving a common and general data manipulation problem with MapReduce. A pattern is not specific to a domain, such as text processing or graph analysis, but it is a general approach to solving a problem. Using design patterns is all about using tried and true design principles to build better software.
Design patterns have been making developers, lives easier for years. They are tools for solving problems in a reusable and general way, so that the developer can spend less time figuring out how they're going to overcome a hurdle and move on to the next one.
This chapter focuses on design patterns that produce a top-level, summarized view of your data, so you can glean insights not available from looking at a localized set of records alone. Aggregation, or summarization, analytics are all about grouping similar data together and then performing an operation, such as calculating a statistic, building an index, or simply...