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From "Owen O'Malley (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7760) BytesWritable / SequenceFile yields dummy linefeed at end as soon as content has one or more linefeeds.
Date Thu, 20 Oct 2011 16:21:10 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7760?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13131725#comment-13131725

Owen O'Malley commented on HADOOP-7760:

You've fallen into a classic mistake with BytesWritable. Note the comment on the API:


You needed to write:

new ByteArrayInputStream(value.getBytes(), 0, value.getLength())
> BytesWritable / SequenceFile yields dummy linefeed at end as soon as content has one
or more linefeeds.
> -------------------------------------------------------------------------------------------------------
>                 Key: HADOOP-7760
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7760
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: record
>    Affects Versions: 0.20.2
>         Environment: Easily reproducable on Debian Linux cluster but also on my Arch
Linux desktop.
> I am aware there are some newer releases in the 0.20 series, but all changelogs and release
note links for those @ http://hadoop.apache.org/common/releases.html are broken, so I can't
check if this has been fixed and/or whether it's safe to upgrade.
>            Reporter: Dieter Plaetinck
>            Priority: Minor
>   Original Estimate: 2h
>  Remaining Estimate: 2h
> I create SequenceFiles which have BytesWritable as values.
> I notice that if I store content which contains no linefeeds ("\n") or one linefeed,
in the value, the value can also be read out of the sequencefile properly.
> However, as soon as I store input which contains two or more linefeeds (which is actually
pretty much always the case), during the process of writing to the sequencefile and reading
my data back, one *extra* linefeed is yielded at the end of the value, a linefeed which did
not exist in the input.
> So this effectively corrupts my data, although i could write a hacky workaround for it.
> I have written a program that demonstrates the behavior, by showing what happens when
writing 2 sequencefiles:
> one that has a record which value contains one linefeeds.
> another that has a record which value contains two linefeeds.
> Upon reading, the latter value will contain 3 linefeeds.
> Test file is : http://pastie.org/2728797

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