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From "Milind Bhandarkar (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-3107) HDFS truncate
Date Tue, 20 Mar 2012 02:49:39 GMT

    [ https://issues.apache.org/jira/browse/HDFS-3107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13233148#comment-13233148
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Milind Bhandarkar commented on HDFS-3107:
-----------------------------------------

What if user accidentally deletes a directory ? You guys never supported me when I asked for
a file-by-file deletion, that could be aborted in time to save 70 pct of users' time, right?
Instead you have always supported a directory deletion with a single misdirected RPC.

Anyway, to answer your question, if user accidentally truncates, he/she can always append
again, without losing any efficiency.

Can we have some mature discussions on this jira please ?

--
Milind Bhandarkar
Chief Architect, Greenplum Labs,
Data Computing Division, EMC
+1-650-523-3858 (W)
+1-408-666-8483 (C)


                
> HDFS truncate
> -------------
>
>                 Key: HDFS-3107
>                 URL: https://issues.apache.org/jira/browse/HDFS-3107
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>          Components: data-node, name-node
>            Reporter: Lei Chang
>         Attachments: HDFS_truncate_semantics_Mar15.pdf
>
>   Original Estimate: 1,344h
>  Remaining Estimate: 1,344h
>
> Systems with transaction support often need to undo changes made to the underlying storage
when a transaction is aborted. Currently HDFS does not support truncate (a standard Posix
operation) which is a reverse operation of append, which makes upper layer applications use
ugly workarounds (such as keeping track of the discarded byte range per file in a separate
metadata store, and periodically running a vacuum process to rewrite compacted files) to overcome
this limitation of HDFS.

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