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From "Raghu Angadi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-4412) hadoop dfs -find feature
Date Tue, 14 Oct 2008 21:57:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-4412?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12639607#action_12639607
] 

Raghu Angadi commented on HADOOP-4412:
--------------------------------------

> The "hadoop dfs -lsr | hadoop dfs -rm" cycle is really, really slow.

This is a general problems for all commands that take multiple files as arguments. Namenode
could support some 'container' versions for some commands(RPCs) like 'rm', 'chmod' so that
it does not need to sync edits log for each file.

> hadoop dfs -find feature
> ------------------------
>
>                 Key: HADOOP-4412
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4412
>             Project: Hadoop Core
>          Issue Type: New Feature
>          Components: dfs
>            Reporter: Marco Nicosia
>
> 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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