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From "Harsh J Chouraria (JIRA)" <j...@apache.org>
Subject [jira] Updated: (MAPREDUCE-2293) Enhance MultipleOutputs to allow additional characters in the named output name
Date Tue, 01 Feb 2011 19:37:29 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-2293?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Harsh J Chouraria updated MAPREDUCE-2293:

    Attachment: mapreduce.mo.removecheck.r1.diff

For extensions to be applied, I think one needs to make a change in the OutputFormat class
chosen. MultipleOutputs can only handle the part before the '-XXXXX' (partition) numbering
in Map/Reduce outputs, not after it.

I've posted a patch that removes the check (from both old and new API). I can't post the result
of an {{ant test-patch}} since that isn't working for me right now (Mumak build is failing
for some reason, in MR trunk). I'll post that when I get it working.

This should be marked as an Incompatible Change in my opinion, as it is a removal of a strong
validation. People may also be relying on the MultiName_OutputName-Partition syntax via string
splits, etc. in the Stable API MO class.

Also, I'm curious to see if allowing any character to go in is a good idea 'Path' wise. Does
HDFS have any restrictions on Filenames? I've not seen a documentation on it (although I think
it is pretty POSIX compliant), but HDFS-13 points out that there may be some trouble, any
thoughts on that?

> Enhance MultipleOutputs to allow additional characters in the named output name
> -------------------------------------------------------------------------------
>                 Key: MAPREDUCE-2293
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2293
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>    Affects Versions: 0.21.0
>            Reporter: David Rosenstrauch
>            Assignee: Harsh J Chouraria
>            Priority: Minor
>         Attachments: mapreduce.mo.removecheck.r1.diff
> Currently you are only allowed to use alpha-numeric characters in a named output name
in the MultipleOutputs class.  This is a bit of an onerous restriction, as it would be extremely
convenient to be able to use non alpha-numerics in the name too.  (E.g., a '.' character would
be very helpful, so that you can use the named output name for holding a file name/extension.
 Perhaps '-' and a '_' characters as well.)
> The restriction seems to be somewhat arbitrary - it appears to be only enforced in the
checkTokenName method.  (Though I don't know if there's any downstream impact by loosening
this restriction.)
> Would be extremely helpful/useful to have this fixed though!

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