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https://issues.apache.org/jira/browse/HADOOP-4927?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz Wo (Nicholas), SZE updated HADOOP-4927:
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Component/s: mapred
Issue Type: Bug (was: New Feature)
> I believe some users did mention that the feature of having exactly N output
> files is useful.
I also believe it is useful in some cases, especially when all output files are
empty (ah, you may argue that the entire job is not useful in this case :) ).
However, it is costly to maintain empty files in HDFS and I believe it is
USELESS in many cases. Could we have an option for not creating them or
cleaning them?
> Part files on the output filesystem are created irrespective of whether the
> corresponding task has anything to write there
> --------------------------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-4927
> URL: https://issues.apache.org/jira/browse/HADOOP-4927
> Project: Hadoop Core
> Issue Type: Bug
> Components: mapred
> Reporter: Devaraj Das
> Fix For: 0.20.0
>
>
> When OutputFormat.getRecordWriter is invoked, a part file is created on the
> output filesystem. But the created RecordWriter is not used until the
> OutputCollector.collect call is made by the task (user's code). This results
> in empty part files even if the OutputCollector.collect is never invoked by
> the corresponding tasks.
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