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https://issues.apache.org/jira/browse/HBASE-15482?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16297084#comment-16297084
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Xiang Li commented on HBASE-15482:
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Regarding the UT:
For mapred, the number of splits generated(=10) is exactly the same as
numRegions specified(=10), while only 8 of them has location not being an empty
array.
For mapreduce, only 8 splits are generated when there is 10 regions.
> Provide an option to skip calculating block locations for SnapshotInputFormat
> -----------------------------------------------------------------------------
>
> Key: HBASE-15482
> URL: https://issues.apache.org/jira/browse/HBASE-15482
> Project: HBase
> Issue Type: Improvement
> Components: mapreduce
> Reporter: Liyin Tang
> Assignee: Xiang Li
> Priority: Minor
> Fix For: 2.1.0
>
> Attachments: 15482.v3.txt, HBASE-15482.master.000.patch,
> HBASE-15482.master.001.patch, HBASE-15482.master.002.patch,
> HBASE-15482.master.003.patch
>
>
> When a MR job is reading from SnapshotInputFormat, it needs to calculate the
> splits based on the block locations in order to get best locality. However,
> this process may take a long time for large snapshots.
> In some setup, the computing layer, Spark, Hive or Presto could run out side
> of HBase cluster. In these scenarios, the block locality doesn't matter.
> Therefore, it will be great to have an option to skip calculating the block
> locations for every job. That will super useful for the Hive/Presto/Spark
> connectors.
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