减速器中有多个输出 [英] Multiple Output in Reducer

问题描述

我正在研究简单的地图缩减程序。我想在缩减器之后为密钥中的每个不同的单词创建不同的文件。例如，在执行Mapreduce之后，我有类似于

Priority1 x 2

Priority1 y 2

Priority1 z 2

priority2 x 2

priority2 y 2

现在我想在缩小阶段之后使用不同的文件，并说优先级1和优先级2根据优先级具有所有这些值。我正在使用java，并想知道应该写在reducer中有这种输出？

我只想知道这是甚至可能或者如果它是如何处理或解决这个问题？
我使用Hadoop 0.20.203，因此multipleoutputs不起作用。

任何指针都会有帮助。
感谢您的帮助！
Atul

解决方案

您需要创建 partioner 类首先，基于你的标准，该部分。

然后你需要创建你自己的 outputformat class和一个 recordwriter class。

recordwriter 类需要根据需要写入不同的文件。此外，如果您需要对值进行排序，请为您的关键字段创建比较器类。

I am working on simple map reduce program. I want to create different files after reducer for each different word in the key. For example, after executing Mapreduce I have something like

Priority1 x 2

Priority1 y 2

Priority1 z 2

priority2 x 2

priority2 y 2

Now I want different files after reduce phase, saying Priority1 and Priority2 which have all these values according to the priority. I am using java and want to know what should be written in reducer for having this kind of output?

I just want to know if this is even possible or if it is how to approach or solve this? I am using Hadoop 0.20.203 and hence multipleoutputs doesn't work.

Any pointers will be helpful. Thanks for the help! Atul

解决方案

You need to create a partioner class first, that partions based on your criteria.

You then need to create your own outputformat class and a recordwriter class.

The recordwriter class, needs to write to different files as per your needs. Further if you need to sort your values create comparator class for your key field.

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