[jira] [Created] (HBASE-20361) Non-succesisve TableInputSplits may wrongly be merged by auto balancing feature

["Yuki Tawara (JIRA)" <ji...@apache.org>]

Yuki Tawara created HBASE-20361:
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             Summary: 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


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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