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This article focuses on "what are the MapReduce design patterns", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn what MapReduce design patterns are.

1 (Total) Summarization Patterns1.1 (Digital Statistics) Numerical Summarizations

This is Built-in, because this is the mode of MapReduce. Equivalent to Count/Max,WordCount in the SQL statement is also the implementation of this.

1.2 (reverse indexing) Inverted Index Summarizations

This name looks very mysterious, in fact, it doesn't feel like a pattern, it can only be regarded as an application, and it doesn't involve the design of MapReduce. Its core essence is the index processing of listof (V3), which is a reference Id. The expected result of this model is:

Url- > list of id

1.3 (counter Statistics) Counting with Counters

The counter is good, fast and easy to use. But the price is to take up tasktracker, the most important thing is to make jobtracker's memory. So in the 1. 0 era, it is recommended that tens, at least

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