James Taylor created OMID-102:
---------------------------------
Summary: Implement visibility filter as pure HBase Filter
Key: OMID-102
URL: https://issues.apache.org/jira/browse/OMID-102
Project: Apache Omid
Issue Type: Bug
Reporter: James Taylor
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().
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
