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https://issues.apache.org/jira/browse/MAPREDUCE-3962?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13225039#comment-13225039
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B Anil Kumar commented on MAPREDUCE-3962:
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Hi Saad,
If you don't specify FileInputFormat explicitly, then It uses TextInputFormat
as defalut. In this case, map input key will be LongWritable and Value will be
Text.
And also you need to set MapOutputKeyClass, MapOutputValueClass, OutPutKeyClass
and OutPutValueClass.
Please take care of above ponits and run the job.
If you can run the job successfully, then please close this issue as invalid.
> InverseMapper causes IntWritable type to collected as Text
> ----------------------------------------------------------
>
> Key: MAPREDUCE-3962
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3962
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 1.0.0
> Reporter: Saad Patel
>
> When using the org.apache.hadoop.mapred.lib.InverseMapper, key,values are
> inversed as expected. For example (Text,IntWritable) will get inversed.
> However, output key,value only works if you use (Text, Text). Below is an
> example, where I was chaining 2 jobs:
> Job 1:
> public static class Reduce extends MapReduceBase implements Reducer<Text,
> IntWritable, Text, IntWritable>{...}
> Job 2:
> conf.setMapperClass(InverseMapper.class);
> public static class Reduce extends MapReduceBase implements
> Reducer<IntWritable, Text, Text, IntWritable> {...} //I would expect this to
> work. When I do this, I get
> java.lang.ClassCastException: org.apache.hadoop.io.Text cannot be cast to
> org.apache.hadoop.io.IntWritable
> To re-inverse my key,values, I had to do this:
> public static class Reduce extends MapReduceBase implements Reducer<Text,
> Text, Text, Text>
> Notice that in order for the reducer to properly accept key,values, I had to
> indicate the key as Text.
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