Yuki Tawara updated HBASE-20361:
    Attachment: HBASE-20361.master.001.patch

> Non-succesisve TableInputSplits may wrongly be merged by auto balancing 
> feature
> -------------------------------------------------------------------------------
>                 Key: HBASE-20361
>                 URL: https://issues.apache.org/jira/browse/HBASE-20361
>             Project: HBase
>          Issue Type: Bug
>          Components: mapreduce
>            Reporter: Yuki Tawara
>            Priority: Major
>         Attachments: HBASE-20361.master.001.patch
> TableInputFormatBase class offers users a mechanism to exclude specific 
> splits from returned list of TableInputFormatBase#getSplits through 
> TableInputFormatBase#includeRegionInSplit.
> It also offers users a feature called "auto balancing" to mitigate data skew 
> by splitting large splits and merging small splits.
> If a user overrides TableInputFormatBase#includeRegionInSplit, i th split and 
> i+1 th split may not be successive(i th split's end key is smaller than i+1 
> th split's start key).
> If he or she further enable auto balancing feature, non-successive splits can 
> be merged, which means excluded splits between merged non-successive splits 
> "revive".
> To avoid such cases, we should not merge non-successive splits.

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