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https://issues.apache.org/jira/browse/MAPREDUCE-2064?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Allen Wittenauer updated MAPREDUCE-2064:
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Fix Version/s: (was: 1.0.4)
> Tutorial should mention SetMapOutputKeyClass
> --------------------------------------------
>
> Key: MAPREDUCE-2064
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2064
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: documentation
> Affects Versions: 0.21.0
> Reporter: Clarence Gardner
> Priority: Minor
> Labels: newbie
>
> The official tutorial (mapred_tutorial.html) (and all other tutorials I've
> seen on the web) show a program that has the same datatypes for the key/value
> pairs emitted by the mapper and by the reducer, and shows a configuration
> call to Job.setOutput{Key,Value}Class but doesn't say that it refers to both
> the mapper and the reducer. It sounds like it refers to the reducer output.
> This might be mentioned in the "Job Configuration" section. Here is a
> possible addition, after the "The Job is used to specify ..." paragraph.
> The job also configures the types of its key/value pairs with
> setOutputKeyClass(type) andsetOutputValueClass(type), which appy to both the
> mapper and reducer classes. If the types output by the mapper and reducer are
> not the same, that should be followed with setMapOutputKeyClass(type) and
> setMapOutputValueClass(type).
> (I'm assuming that at least a call to setOutput{Key,Value}Class is required.)
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