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https://issues.apache.org/jira/browse/HBASE-17177?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Duo Zhang updated HBASE-17177:
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    Summary: Compaction can break the region/row level atomic when scan even if 
we pass mvcc to client  (was: Major compaction can break the region/row level 
atomic when scan even if we pass mvcc to client)

> 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
>             Fix For: 2.0.0, 1.4.0
>
>
> 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 kept.



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