[jira] [Created] (HIVE-18864) WriteId high water mark (HWM) is incorrect if ValidWriteIdList is obtained after allocating writeId by current transaction.

["Sankar Hariappan (JIRA)" <ji...@apache.org>]

Sankar Hariappan created HIVE-18864:
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             Summary: WriteId high water mark (HWM) is incorrect if ValidWriteIdList is obtained after allocating writeId by current transaction.
                 Key: HIVE-18864
                 URL: https://issues.apache.org/jira/browse/HIVE-18864
             Project: Hive
          Issue Type: Sub-task
          Components: Transactions
    Affects Versions: 3.0.0
            Reporter: Sankar Hariappan
            Assignee: Sankar Hariappan
             Fix For: 3.0.0


For multi-statement txns, it is possible that write on a table happens after a read. Let's see the below scenario.
 # Committed txn=9 writes on table T1 with writeId=5.
 # Open txn=10. ValidTxnList(open:null, txn_HWM=10),
 # Read table T1 from txn=10. ValidWriteIdList(open:null, write_HWM=5).
 # Open txn=11, writes on table T1 with writeid=6.
 # Read table T1 from txn=10. ValidWriteIdList(open:null, write_HWM=5).
 # Write table T1 from txn=10 with writeId=7.
 # Read table T1 from txn=10. {color:#d04437}*ValidWriteIdList(open:null, write_HWM=7)*. – This read will able to see rows added by txn=11 which is still open.{color}

{color:#d04437}{color:#333333}So, it is needed to rebuild the open/aborted list of ValidWriteIdList based on txn_HWM. Any writeId allocated by txnId > txn_HWM should be marked as open.{color}
{color}



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