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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6085) Facilitate processing of text files without key/value split
Date Thu, 11 Sep 2014 16:23:34 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14130234#comment-14130234

Hadoop QA commented on MAPREDUCE-6085:

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  against trunk revision 4be9517.

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:red}-1 tests included{color}.  The patch doesn't appear to include any new or modified
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of
javac compiler warnings.

    {color:green}+1 javadoc{color}.  There were no new javadoc warning messages.

    {color:green}+1 eclipse:eclipse{color}.  The patch built with eclipse:eclipse.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new Findbugs (version
2.0.3) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase the total number
of release audit warnings.

    {color:green}+1 core tests{color}.  The patch passed unit tests in hadoop-tools/hadoop-streaming.

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4869//testReport/
Console output: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4869//console

This message is automatically generated.

> Facilitate processing of text files without key/value split
> -----------------------------------------------------------
>                 Key: MAPREDUCE-6085
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6085
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>    Affects Versions: 2.4.1
>            Reporter: Dmitry Sivachenko
>         Attachments: IdentifierResolver1.java.patch
> There is a rather popular type of task: processing of text files line by line without
splitting line to key/value pair in streaming mode.  (UNIX commands like grep, awk, etc, any
filter scripts).
> By default, Hadoop streaming interface uses TextInputFormat which suites well for this
task: it passes the input line itself to streaming job stdin.
> TextOutputReader class, which receives streaming job's output, splits it for key and
value pair, and TextOutputFormat tries to merge this pair with separator.
> This results in extra separator appearing in the output in some cases.
> KeyOnlyTextOutputReader solves this problem: it passes the whole line as a key with null
value, and TextOutputFormat correctly writes it without any separators inserted.
> I propose to add another IdentifierResolver: "keyonlytextoutput", which uses standard
TextInputWriter but replaces TextOutputReader with KeyOnlyTextOutputReader).
> As a result, lines of text are never split into key/value pair and never joined back,
so lines appear in the output unmodified.

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