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https://issues.apache.org/jira/browse/HDFS-6492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14019331#comment-14019331
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Andrew Wang commented on HDFS-6492:
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For HDFS-6134, we need to set both a key and IV for newly-created encrypted
files. It'd be better to not do this as separate edit log ops, since it means
we need to deal with a file with no xattrs, or just a key but no IV. Thus,
create/mkdir time xattrs. Multi-set seems potentially useful for similar
reasons, so let's future-proof the metadata format before it gets released.
I'll also note that clients can pack multiple k-v pairs into a single xattr via
something like protobuf, and then do a read/modify/write to do atomic
multi-updates. So, even if we don't immediately expose multi-set to clients,
they still have somewhat worse workarounds available.
> Support create-time xattrs and atomically setting multiple xattrs
> -----------------------------------------------------------------
>
> Key: HDFS-6492
> URL: https://issues.apache.org/jira/browse/HDFS-6492
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 3.0.0
> Reporter: Andrew Wang
> Assignee: Andrew Wang
>
> Ongoing work in HDFS-6134 requires being able to set system namespace
> extended attributes at create and mkdir time, as well as being able to
> atomically set multiple xattrs at once. There's currently no need to expose
> this functionality in the client API, so let's not unless we have to.
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