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From "Duo Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-17177) Major compaction can break the region/row level atomic when scan even if we pass mvcc to client
Date Sat, 26 Nov 2016 14:41:59 GMT
Duo Zhang created HBASE-17177:
---------------------------------

             Summary: Major compaction can break the region/row level atomic when scan even
if we pass mvcc to client
                 Key: HBASE-17177
                 URL: https://issues.apache.org/jira/browse/HBASE-17177
             Project: HBase
          Issue Type: Sub-task
          Components: scan
            Reporter: Duo Zhang


We know that major compaction will actually delete the cells which are deleted by a delete
marker. In order to give a consistent view for a scan, we need to use a map to track the read
points for all scanners for a region, and the smallest one will be used for a compaction.
For all delete markers whose mvcc is greater than this value, we will not use it to delete
other cells.

And the problem for a scan restart after region move is that, the new RS does not have the
information of the scanners opened at the old RS before the client sends scan requests to
the new RS which means the read points map is incomplete and the smallest read point maybe
greater than the correct value. So if a major compaction happens at that time, it may delete
some cells which should be keeped.



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