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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1700) Append to files in HDFS
Date Wed, 23 Jul 2008 13:21:32 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12616006#action_12616006
] 

dhruba borthakur commented on HADOOP-1700:
------------------------------------------

I had an offline discussion with Nicholas, Sameer, Rob Chansler and Nigel. We agreed that
we will open a couple od JIRAs (marked as blockers for 0.19), these will be related to documentation,
writing more unit tests, creating a append-benchmark and running large-scale tests to validate
existing behaviour and performance.  Rob has volunteered to create these JIRAs. Once these
are created, we should check in this patch. 

This means that it is likely that this patch gets checked into trunk in a day or two.

> Append to files in HDFS
> -----------------------
>
>                 Key: HADOOP-1700
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1700
>             Project: Hadoop Core
>          Issue Type: New Feature
>          Components: dfs
>    Affects Versions: 0.15.1
>            Reporter: stack
>            Assignee: dhruba borthakur
>         Attachments: 1700_20080606.patch, append.patch, append3.patch, Appends.doc, Appends.doc,
Appends.html, appendtrunk10.patch, appendtrunk11.patch, appendtrunk12.patch, appendtrunk13.patch,
appendtrunk13.patch, appendtrunk13.patch, appendtrunk14.patch, appendtrunk14.patch, appendtrunk15.patch,
appendtrunk6.patch, appendtrunk7.patch, appendtrunk8.patch, appendtrunk9.patch, Grid_HadoopRenumberBlocks.pdf
>
>
> Request for being able to append to files in HDFS has been raised a couple of times on
the list of late.   For one example, see http://www.nabble.com/HDFS%2C-appending-writes-status-tf3848237.html#a10916193.
 Other mail describes folks' workarounds because this feature is lacking: e.g. http://www.nabble.com/Loading-data-into-HDFS-tf4200003.html#a12039480
(Later on this thread, Jim Kellerman re-raises the HBase need of this feature).  HADOOP-337
'DFS files should be appendable' makes mention of file append but it was opened early in the
life of HDFS when the focus was more on implementing the basics rather than adding new features.
 Interest fizzled.  Because HADOOP-337 is also a bit of a grab-bag -- it includes truncation
and being able to concurrently read/write -- rather than try and breathe new life into HADOOP-337,
instead, here is a new issue focused on file append.  Ultimately, being able to do as the
google GFS paper describes -- having multiple concurrent clients making 'Atomic Record Append'
to a single file would be sweet but at least for a first cut at this feature, IMO, a single
client appending to a single HDFS file letting the application manage the access would be
sufficent.

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