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https://issues.apache.org/jira/browse/HADOOP-8989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13506017#comment-13506017
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Jonathan Allen commented on HADOOP-8989:
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Allen - I haven't done any specific studies of the NN impact but I would expect
it to be the same as any of the existing recursive command (e.g. ls -R). The
code uses the existing recursion code and applies the expressions to the
returned FileStatus on the client side. The -exec option obviously impacts the
NN but no more than if you ran the command directly (though you don't have the
JVM start-up overhead so the rate of NN messages will be higher).
Wolfgang - I'll look at adding those option expressions in (I got to the point
where it looked like I'd be adding expressions forever so I decided to stop and
see what people asked for).
Daryn - if you do get a chance to review this then the main code is pretty much
finished (though I need to sort out the formatting before submitting properly)
but I've reworked the unit tests since uploading the last patch (I'll upload a
new at the weekend). I still need to update the documentation web page and add
some stuff in the CLI test suites.
> hadoop dfs -find feature
> ------------------------
>
> Key: HADOOP-8989
> URL: https://issues.apache.org/jira/browse/HADOOP-8989
> Project: Hadoop Common
> Issue Type: New Feature
> Reporter: Marco Nicosia
> Assignee: Jonathan Allen
> Attachments: HADOOP-8989.patch, HADOOP-8989.patch, HADOOP-8989.patch
>
>
> Both sysadmins and users make frequent use of the unix 'find' command, but
> Hadoop has no correlate. Without this, users are writing scripts which make
> heavy use of hadoop dfs -lsr, and implementing find one-offs. I think hdfs
> -lsr is somewhat taxing on the NameNode, and a really slow experience on the
> client side. Possibly an in-NameNode find operation would be only a bit more
> taxing on the NameNode, but significantly faster from the client's point of
> view?
> The minimum set of options I can think of which would make a Hadoop find
> command generally useful is (in priority order):
> * -type (file or directory, for now)
> * -atime/-ctime-mtime (... and -creationtime?) (both + and - arguments)
> * -print0 (for piping to xargs -0)
> * -depth
> * -owner/-group (and -nouser/-nogroup)
> * -name (allowing for shell pattern, or even regex?)
> * -perm
> * -size
> One possible special case, but could possibly be really cool if it ran from
> within the NameNode:
> * -delete
> The "hadoop dfs -lsr | hadoop dfs -rm" cycle is really, really slow.
> Lower priority, some people do use operators, mostly to execute -or searches
> such as:
> * find / \(-nouser -or -nogroup\)
> Finally, I thought I'd include a link to the [Posix spec for
> find|http://www.opengroup.org/onlinepubs/009695399/utilities/find.html]
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