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https://issues.apache.org/jira/browse/HBASE-21672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16737370#comment-16737370
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Nihal Jain commented on HBASE-21672:
------------------------------------

{quote}Shouldn't this either be a no-op for filesystems that don't have 
locality, or something we can just ask the filesystem?
{quote}
The file-system does not directly return anything as locality as such. We have 
some logic to calculate it in hbase. it is based on {{HDFSBlocksDistribution}} 
information which we create using block location information returned by under 
lying fs.

I think this solution should be fine, and will be useful, given we know our fs 
would not do us any good and may waste cpu cycles in creating this 
{{HDFSBlocksDistribution}} information. In fact we already have something 
similar in HBase, see 
[HBASE-18478|https://issues.apache.org/jira/browse/HBASE-18478].

> Allow skipping HDFS block distribution computation
> --------------------------------------------------
>
>                 Key: HBASE-21672
>                 URL: https://issues.apache.org/jira/browse/HBASE-21672
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Nihal Jain
>            Assignee: Nihal Jain
>            Priority: Major
>              Labels: S3
>
> We should have a configuration to skip HDFS block distribution calculation in 
> HBase. For example on file systems that do not surface locality such as S3, 
> calculating block distribution would not be any useful.
> Currentlly, we do not have a way to skip hdfs block distribution computation. 
> For this, we can provide a new configuration key, say 
> {{hbase.block.distribution.skip.computation}} (which would be {{false}} by 
> default).
> Users using filesystems such as s3 may choose to make this {{true}}, thus 
> skipping block distribution computation.



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