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https://issues.apache.org/jira/browse/HADOOP-1700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12525365
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eric baldeschwieler commented on HADOOP-1700:
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Why would the name node not keep the timestamp/version? Seems to me it will
need it to disambiguate new block reports and such. We can afford the bytes
IMO.
Those statements about "reasonably synchronized clocks" worry me. Especially
if clients or datanodes are producing them. If the name node is not the source
of truth, I'm afraid we can introduce weird cases.
I think the next logical step here is for us to outline a more detail proposal
for review. I think this is going to take a couple of distinct steps. We can
outline those and get to agreement on the basics.
Jim's request that a file exist if its producer dies before a close sounds like
it would be easy, but then we get to flush semantics... I take it you don't
just want the last complete 128M block Jim? If you want the last "log line"
then you need something similar to what I outlined.
> Append to files in HDFS
> -----------------------
>
> Key: HADOOP-1700
> URL: https://issues.apache.org/jira/browse/HADOOP-1700
> Project: Hadoop
> Issue Type: New Feature
> Components: dfs
> Reporter: stack
>
> 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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