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https://issues.apache.org/jira/browse/HADOOP-4044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12630292#action_12630292
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Joydeep Sen Sarma commented on HADOOP-4044:
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wrt Allen's comment - i think it's not without merit. he's probably thinking
about moving things within the same hdfs instance - in which case having to
have a symlink per leaf is going to lead to doubling of inodes (for the subtree
being moved).
Couple of orthogonal ideas:
1. would it not be easy to write a new file system client that does component
by component lookup? (instead of DFSClient behavior). this would not seem to
require any namenode changes.
2. support symlinks only within the same hdfs instance. the namenode can
resolve things internally - no changes to the client.
then we can combine these two approaches. The namenode can return specific
error if it finds the path to be resolved has reference to external fs (using
work done in #2). The regular DFSClient can revert to special client file
system that does component by component lookup (work done in #1) in case of
this error. this will prevent having to incur the overhead of component by
component lookup unless one hits a symlink that crosses fs boundary.
> Create symbolic links in HDFS
> -----------------------------
>
> Key: HADOOP-4044
> URL: https://issues.apache.org/jira/browse/HADOOP-4044
> Project: Hadoop Core
> Issue Type: New Feature
> Components: dfs
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: symLink1.patch, symLink1.patch
>
>
> HDFS should support symbolic links. A symbolic link is a special type of file
> that contains a reference to another file or directory in the form of an
> absolute or relative path and that affects pathname resolution. Programs
> which read or write to files named by a symbolic link will behave as if
> operating directly on the target file. However, archiving utilities can
> handle symbolic links specially and manipulate them directly.
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