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ASF GitHub Bot commented on OMID-102: ------------------------------------- Github user JamesRTaylor commented on a diff in the pull request: https://github.com/apache/incubator-omid/pull/41#discussion_r207918920 --- Diff: hbase-client/src/main/java/org/apache/omid/transaction/HTableAccessWrapper.java --- @@ -20,10 +20,7 @@ import java.io.IOException; import java.util.List; -import org.apache.hadoop.hbase.client.Get; -import org.apache.hadoop.hbase.client.HTableInterface; -import org.apache.hadoop.hbase.client.Put; -import org.apache.hadoop.hbase.client.Result; +import org.apache.hadoop.hbase.client.*; --- End diff -- Was the use of wildcarding here intentional? Not sure about Omid, but in Phoenix we always explicitly specify all the imports. > 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(). -- This message was sent by Atlassian JIRA (v7.6.3#76005)