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https://issues.apache.org/jira/browse/HDFS-9607?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15114620#comment-15114620
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Dinesh S. Atreya commented on HDFS-9607:
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Konstantin,
First thank you for the positive comments regarding feasibility. Yes your
assumption is essentially correct: this JIRA is about random updates, random
write-in-place, random read-write, specifically random read-copy-write.
However, I want to be careful regarding random writes on the get go. Even
though HDFS files stores bytes, from a users perspective, these bytes could be
finance data or personal contact data or some customer order data etc., that
the user may not want to get corrupted. Most often this data will be read first
before getting updated, hence *_random updates, random write-in-place, random
read-write, specifically random read-copy-write_* (unless the data is an
append/insert which HDFS already supports).
(Hence I am a little bit apprehensive regarding adding just one positional
write method to DFSOutputStream)
So semantically we want to propose *random updates* with *canWrite* checks that
check against the length that was read first. These checks can be relaxed as
needed and provide random write capabilities.
> Advance Hadoop Architecture (AHA) - HDFS Update
> -----------------------------------------------
>
> Key: HDFS-9607
> URL: https://issues.apache.org/jira/browse/HDFS-9607
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Dinesh S. Atreya
>
> Link to Umbrella JIRA
> https://issues.apache.org/jira/browse/HADOOP-12620
> Provide capability to carry out in-place writes/updates. Only writes in-place
> are supported where the existing length does not change.
> For example, "Hello World" can be replaced by "Hello HDFS!"
> See
> https://issues.apache.org/jira/browse/HADOOP-12620?focusedCommentId=15046300&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15046300
> for more details.
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