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

     [ https://issues.apache.org/jira/browse/HDFS-5793?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Haohui Mai updated HDFS-5793:
-----------------------------

    Attachment: HDFS-5793.000.patch

> 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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