Peter Vary created HIVE-22122:
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             Summary: TxnHandler.getValidWriteIdsForTable optimization for 
compacted tables
                 Key: HIVE-22122
                 URL: https://issues.apache.org/jira/browse/HIVE-22122
             Project: Hive
          Issue Type: Bug
          Components: Transactions
            Reporter: Peter Vary


When we do not find open writes for the given validTxnList then we either:
 # do not have any writes on the table - we can return writeIdHwm = 0, and no 
invalid/aborted writes;
 # we have only compacted writes on the table - we can return writeIdHwm = 
nextWriteId -1, and no invalid/aborted;
 # we have compacted writes and some invalid writes on the table - we can 
return the lowest invalid write as a writeIdHwm and set it as invalid.

What the current code does instead is sending writeIdHwm = nextWriteId -1, and 
sending every write as invalid. This results the same response in case 1-2, but 
probably a longer list in case 3.

So we have place for some optimizations



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