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This article mainly explains "how to use the hadoop map function", the content of the explanation is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "how to use the hadoop map function" bar!

After the execution of the map function, there are a total of four map outputs, namely

Partition. There is only one partition by default.

Sort

Grouping puts the value of the same key into a collection, and each group calls the reduce function once

Reduction (optional)

The temporary results of the output of the map task are stored on linux disk.

Common configurations:

Hdfs-site.xml

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