The reducer output is not created if the mapper input is empty
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Key: HADOOP-4251
URL: https://issues.apache.org/jira/browse/HADOOP-4251
Project: Hadoop Core
Issue Type: Bug
Components: mapred
Reporter: Namit Jain
Assignee: Namit Jain
For some Hive stuff, I ran into the following scenario:
For a given map-reduce job, the input was empty. Because of that no mappers and
reducers were created. It would have been helpful if an empty output for the
reducer would have been created.
After browsing though the code, it seems that in initTasks() in JobInProgress,
no mappers and reducers are initialized if input is empty.
I was thinking of putting a fix there. If the input is empty, before returning,
create the output directory (as specified by the reducer) if needed.Any
comments/suggestions....
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