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Posted to common-issues@hadoop.apache.org by "Andras Bokor (JIRA)" <ji...@apache.org> on 2018/01/26 14:40:00 UTC
[jira] [Resolved] (HADOOP-9697) Mapper example
[ https://issues.apache.org/jira/browse/HADOOP-9697?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andras Bokor resolved HADOOP-9697.
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Resolution: Not A Problem
It this example the key is not used. It's a common think that the key is Object when it is not used.
I think we should force the users to use WritableComparable with generics but that is out of this ticket's scope.
> Mapper example
> --------------
>
> Key: HADOOP-9697
> URL: https://issues.apache.org/jira/browse/HADOOP-9697
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: DeepakVohra
> Priority: Minor
>
> The org.apache.hadoop.mapreduce
> Class Mapper<KEYIN,VALUEIN,KEYOUT,VALUEOUT>
> has an example with
> public void map(Object key, Text value, Context context)
> But, "Any type which is to be used as a key in the Hadoop Map-Reduce framework should implement this interface."
> org.apache.hadoop.io
> Interface WritableComparable<T>
> The example has Object for key type. Object doesn't implement WritableComparable.
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