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https://issues.apache.org/jira/browse/OMID-102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16571342#comment-16571342
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ASF GitHub Bot commented on OMID-102:
-------------------------------------

Github user yonigottesman commented on the issue:

    https://github.com/apache/incubator-omid/pull/41
  
    All FlappingTransactionIT tests pass


> Implement visibility filter as pure HBase Filter
> ------------------------------------------------
>
>                 Key: OMID-102
>                 URL: https://issues.apache.org/jira/browse/OMID-102
>             Project: Apache Omid
>          Issue Type: Sub-task
>            Reporter: James Taylor
>            Assignee: Yonatan Gottesman
>            Priority: Major
>
> The way Omid currently filters through it's own RegionScanner won't work the 
> way it's implemented (i.e. the way the filtering is done *after* the next 
> call). The reason is that the state of HBase filters get messed up since 
> these filters will start to see cells that it shouldn't (i.e. cells that 
> would be filtered based on snapshot isolation). It cannot be worked around by 
> manually running filters afterwards because filters may issue seek calls 
> which are handled during the running of scans by HBase.
>  
> Instead, the filtering needs to be implemented as a pure HBase filter and 
> that filter needs to delegate to the other, delegate filter once it's 
> determined that the cell is visible. See Tephra's TransactionVisibilityFilter 
> and they way it calls the delegate filter (cellFilters) only after it's 
> determined that the cell is visible. You may run into TEPHRA-169 without 
> including the CellSkipFilter too. 
> Because it'll be easier if you see shadow cells *before* their corresponding 
> real cells you can prefix instead of suffix the column qualifiers to 
> guarantee that you'd see the shadow cells prior to the actual cells. Or you 
> could buffer cells in your filter prior to omitting them. Another issue would 
> be if the shadow cells aren't found and you need to consult the commit table 
> - I suppose if the shadow cells are first, this logic would be easier to know 
> when it needs to be called.
>  
> To reproduce, see the Phoenix unit tests 
> FlappingTransactionIT.testInflightUpdateNotSeen() and 
> testInflightDeleteNotSeen().



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