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https://issues.apache.org/jira/browse/MAPREDUCE-5457?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sandy Ryza updated MAPREDUCE-5457:
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Description:
MR jobs sometimes want to just output lines of text, not key/value pairs.
TextOutputFormat handles this by, if a null value is given, outputting only the
key with no separator. Streaming jobs are unable to take advantage of this,
because they can't output null values. A text output format reader takes each
line as a key and outputs NullWritables for values would allow streaming jobs
to output lines of text.
was:
MR jobs sometimes want to just output lines of text, not key/value pairs.
TextOutputFormat handles this by, if a null value is given, outputting only the
key with no separator. Streaming jobs are unable to take advantage of this,
because they can't output null values. A text output format that ignores
values and only outputs keys would allow streaming jobs to output lines of
text.
> Add a KeyOnlyTextOutputReader to enable streaming to write out text files
> without separators
> --------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5457
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5457
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Affects Versions: 2.1.0-beta
> Reporter: Sandy Ryza
>
> MR jobs sometimes want to just output lines of text, not key/value pairs.
> TextOutputFormat handles this by, if a null value is given, outputting only
> the key with no separator. Streaming jobs are unable to take advantage of
> this, because they can't output null values. A text output format reader
> takes each line as a key and outputs NullWritables for values would allow
> streaming jobs to output lines of text.
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