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From "Haohui Mai (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-5793) Optimize the serialization of PermissionStatus
Date Thu, 16 Jan 2014 22:27:19 GMT
Haohui Mai created HDFS-5793:

             Summary: 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
         Attachments: HDFS-5793.000.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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