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https://issues.apache.org/jira/browse/HDFS-512?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hairong Kuang updated HDFS-512:
-------------------------------

    Attachment: blockKey.patch

This patch change Block's key from block id+generation stamp to be block id. It 
also removes the class GenerationStamp and the use of generation wild card.

> Set block id as the key to Block
> --------------------------------
>
>                 Key: HDFS-512
>                 URL: https://issues.apache.org/jira/browse/HDFS-512
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>    Affects Versions: 0.21.0
>            Reporter: Hairong Kuang
>            Assignee: Hairong Kuang
>             Fix For: 0.21.0
>
>         Attachments: blockKey.patch
>
>
> Currently the key to Block is block id + generation stamp. I would propose to 
> change it to be only block id. This is based on the following properties of 
> the dfs cluster:
> 1. On each datanode only one replica of block exists. Therefore there is only 
> one generation of a block.
> 2. NameNode has only one entry for a block in its blocks map.
> With this change, search for a block/replica's meta information is easier 
> since most of the time we know a block's id but may not know its generation 
> stamp.

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