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From "Robert Chansler (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-1700) Append to files in HDFS
Date Thu, 17 Jul 2008 17:57:32 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-1700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12614472#action_12614472

Robert Chansler commented on HADOOP-1700:

This is a substantial new feature, and 0.18 is still waiting on the fixes to previous changes
needed to facilitate append.

Konstantin's previous comment has some useful detail about necessary unit  tests. Also there
is a necessity for at-scale functional testing.

Has there been any functional testing from application programs? At challenging load levels?
In competition with other activity?

Has performance testing established that append changes do not have an adverse impact on other

Does the design documentation need to be updated since November?

What about user documentation?

> 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, 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

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