[jira] [Created] (CALCITE-6448) FilterReduceExpressionsRule returns empty RelNode for RexLiterals

[Soumyakanti Das (Jira)]

Soumyakanti Das created CALCITE-6448:
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             Summary: FilterReduceExpressionsRule returns empty RelNode for 
RexLiterals
                 Key: CALCITE-6448
                 URL: https://issues.apache.org/jira/browse/CALCITE-6448
             Project: Calcite
          Issue Type: Bug
          Components: core
            Reporter: Soumyakanti Das


In Hive, for simple queries with {{WHERE 'foo'}} we get an empty result, where 
as for simple queries with {{WHERE t.stringColumn}} we get non-empty result.

Currently in {{FilterReduceExpressionsRule}}, all {{RexLiteral}}s are converted 
to empty values by 


{code:java}
else if (newConditionExp instanceof RexLiteral
  || RexUtil.isNullLiteral(newConditionExp, true)) {
call.transformTo(createEmptyRelOrEquivalent(call, filter));
{code}

This might be not inline with {{RexLiteral#isAlwaysFalse}}, and it might be 
safer to leave the literal as it is.



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