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https://issues.apache.org/jira/browse/HDFS-17120?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17747825#comment-17747825
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ASF GitHub Bot commented on HDFS-17120:
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umamaheswararao commented on PR #5885:
URL: https://github.com/apache/hadoop/pull/5885#issuecomment-1653089202
Thanks @sadanand48 for the contribution. Thanks @swamirishi and @ayushtkn
for the reviews.
> Support snapshot diff based copylisting for flat paths.
> -------------------------------------------------------
>
> Key: HDFS-17120
> URL: https://issues.apache.org/jira/browse/HDFS-17120
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Sadanand Shenoy
> Assignee: Sadanand Shenoy
> Priority: Major
> Labels: pull-request-available
>
> Currently for Diff-based copyListing that is used during the distcpSync step
> of an incremental copy by default the SimpleCopyListing implementation is
> used. In it's implementation it iterates through the DiffReport and if the
> DiffType is Create and the path is a directory, it recursively traverses the
> directory and adds the subpaths to the resultant copyList.
> This works fine for implementations of snapshotDiff that include only
> top-level directories as part of its DiffReport . Suppose a snapshotDiff
> implementation outputs only flat paths that include both the directory and
> sub-directory subpath in its DiffReport, it will lead to duplicate paths in
> the copyList and throws DuplicateFileException.
>
> For example
> Ozone filesystem implementation of snapdiff b/w 2 snapshots shows all
> subpaths as part of the diff.
> {code:java}
> [~]# ozone sh snapshot create vol11/buck1 snap1
> [~]# ozone sh snapshot create vol11/buck2 snap1
> [~]# ozone fs -mkdir ofs://ozone1/vol11/buck1/dir1
> [ ~]# ozone fs -mkdir ofs://ozone1/vol11/buck1/dir1/dir11
> [ ~]# ozone fs -mkdir ofs://ozone1/vol11/buck1/dir1/dir11/dir111
> [~]# ozone sh snapshot create vol11/buck1 snap2
> [~]# ozone sh snapshot diff vol11/buck1 snap1 snap2
> Difference between snapshot: snap1 and snapshot: snap2
> + ./dir1
> + ./dir1/dir11
> + ./dir1/dir11/dir111 {code}
> we can see even though dir11 & dir111 are subpaths they are present in
> snapdiff , This is not the case for HDFS though.
> This Jira aims to create a new copyListing impl that is used for diff based
> copyListing that doesn't traverse the directory but only adds paths that are
> present in its diff.
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