Eugene Koifman created HIVE-21114:
-------------------------------------

             Summary: Create read-only transactions
                 Key: HIVE-21114
                 URL: https://issues.apache.org/jira/browse/HIVE-21114
             Project: Hive
          Issue Type: Bug
          Components: Transactions
    Affects Versions: 4.0.0
            Reporter: Eugene Koifman


With HIVE-21036 we have a way to indicate that a txn is read only.
We should (at least in auto-commit mode) determine if the single stmt is a read 
and mark the txn accordingly.  
Then we can optimize {{TxnHandler.commitTxn()}} so that it doesn't do any 
checks in write_set etc.
HiveOperation only has QUERY, which includes Insert and Select, so this 
requires figuring out how to determine if a query is a SELECT.  By the time 
{{Driver.openTransaction();}} is called, we have already parsed the query so 
there should be a way to know if the statement only reads.

For multi-stmt txns (once these are supported) we should allow user to indicate 
that a txn is read-only and then not allow any statements that can make 
modifications in this txn.  This should be a different jira.

cc [~ikryvenko]



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