hadoop.ma preD VS hadoop.ma preduce？ [英] hadoop.mapred vs hadoop.mapreduce?

问题描述

为什么有两个独立的包的map-reduce Apache的Hadoop的包树包：

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

org.apache.hadoop.mapred 

<一个href=\"http://javasource$c$c.org/html/open-source/hadoop/hadoop-1.0.3/org/apache/hadoop/ma$p$pd/\">http://javasource$c$c.org/html/open-source/hadoop/hadoop-1.0.3/org/apache/hadoop/ma$p$pd/

org.apache.hadoop.mapreduce

<一个href=\"http://javasource$c$c.org/html/open-source/hadoop/hadoop-1.0.3/org/apache/hadoop/ma$p$pduce/\">http://javasource$c$c.org/html/open-source/hadoop/hadoop-1.0.3/org/apache/hadoop/ma$p$pduce/

他们为什么要分离出来？是否有明确本文档？

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

推荐答案

他们被分离出来，因为这两个包的重新present两种不同的API。 org.apache.hadoop.ma preD 是旧的API和 org.apache.hadoop.ma preduce 是新的。事情就这样让程序员编写马preduce作业更方便，更轻松，精致时尚。您可能会发现此 presentation 有用的，其中谈到了详细差异。

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.

希望这回答了你的问题。

Hope this answers your question.

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