hadoop.mapred 与 hadoop.mapreduce? [英] hadoop.mapred vs hadoop.mapreduce?

问题描述

为什么Apache的hadoop包树中有两个独立的包map-reduce包:

Why are there two separate packages map-reduce package in Apache's hadoop package tree:

org.apache.hadoop.mapred 

http://javasourcecode.org/html/open-source/hadoop/hadoop-1.0.3/org/apache/hadoop/mapred/

org.apache.hadoop.mapreduce

http://javasourcecode.org/html/open-source/hadoop/hadoop-1.0.3/org/apache/hadoop/mapreduce/

他们为什么分开?是否有文件澄清这一点?

Why are they separated out? Is there documentation that clarifies this?

推荐答案

它们是分开的，因为这两个包代表 2 个不同的 API.org.apache.hadoop.mapred 是旧 API，org.apache.hadoop.mapreduce 是新 API.这样做是为了让程序员以更方便、更简单和更复杂的方式编写 MapReduce 作业.您可能会发现这个 presentation 很有用，它详细讨论了差异.

They are separated out because both of these packages represent 2 different APIs. org.apache.hadoop.mapred is the older API and org.apache.hadoop.mapreduce is the new one. And it was done to allow programmers write MapReduce jobs in a more convenient, easier and sophisticated fashion. You might find this presentation useful, which talks about the differences in detail.

希望这能回答您的问题.

Hope this answers your question.

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