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https://issues.apache.org/jira/browse/HDFS-5293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13785706#comment-13785706
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Colin Patrick McCabe commented on HDFS-5293:
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If we're going to do this, why not just make all NN operations resolve symlinks
as far as they can? That would remove all the performance concerns about
returning unresolved paths, at least in the context of non-cross-FS symlinks.
We already have many filesystems that do symlink resolution internally, such as
LocalFileSystem, Ceph, etc. etc. If HDFS's namenode did symlink resolution for
all RPCs, we could return unresolved paths everywhere and be happy.
> Symlink resolution requires unnecessary RPCs
> --------------------------------------------
>
> Key: HDFS-5293
> URL: https://issues.apache.org/jira/browse/HDFS-5293
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.0.0-alpha, 3.0.0
> Reporter: Daryn Sharp
> Priority: Critical
>
> When the NN encounters a symlink, it throws an {{UnresolvedLinkException}}.
> This exception contains only the path that is a symlink. The client issues
> another RPC to obtain the link target, followed by another RPC with the link
> target + remainder of the original path.
> {{UnresolvedLinkException}} should be returning both the link and the target
> to avoid a costly and unnecessary intermediate RPC to obtain the link target.
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