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https://issues.apache.org/jira/browse/HDFS-5793?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jing Zhao resolved HDFS-5793.
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Resolution: Fixed
Fix Version/s: HDFS-5698 (FSImage in protobuf)
Hadoop Flags: Reviewed
I've committed this.
> Optimize the serialization of PermissionStatus
> ----------------------------------------------
>
> Key: HDFS-5793
> URL: https://issues.apache.org/jira/browse/HDFS-5793
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Haohui Mai
> Assignee: Haohui Mai
> Fix For: HDFS-5698 (FSImage in protobuf)
>
> Attachments: HDFS-5793.000.patch, HDFS-5793.001.patch
>
>
> {{PermissionStatus}} contains the user name, the group name and the
> permission. It is serialized into two strings and a short.
> Note that the size of unique user / groups names are relatively small, thus
> this format has some performance penalties. The names are stored multiple
> times, increasing both the storage size and the overhead of reconstructing
> the names.
> This jira proposes to serialize {{PermissionStatus}} similar to its in-memory
> layout. The code can record a mapping between user / group names and ids, and
> pack user / group / permission into a single 64-bit long.
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