James Taylor commented on OMID-102:

Agree, [~yonigo], it's a good idea to do the same wrapping that Tephra does for 
the same reason. Would be good to understand at which version of HBase this is 
no longer necessary. We could try updating the pom to the latest version of 
HBase on the 4.x-HBase-1.4 branch and see if it's still necessary.

> 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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