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Posted to mapreduce-issues@hadoop.apache.org by "Sandy Ryza (JIRA)" <ji...@apache.org> on 2013/10/09 03:14:42 UTC

[jira] [Updated] (MAPREDUCE-5457) Add a KeyOnlyTextOutputReader to enable streaming to write out text files without separators

     [ https://issues.apache.org/jira/browse/MAPREDUCE-5457?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sandy Ryza updated MAPREDUCE-5457:
----------------------------------

    Attachment: MAPREDUCE-5457-branch-1.patch

> 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
>            Assignee: Sandy Ryza
>         Attachments: MAPREDUCE-5457-branch-1.patch, MAPREDUCE-5457.patch
>
>
> 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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