[GitHub] drill issue #517: DRILL-4704 fix

[jinfengni <gi...@git.apache.org>]

Github user jinfengni commented on the issue:

    https://github.com/apache/drill/pull/517
  
    I agreed with Aman that the eval() of CastIntDecimal28Sparse() should not ignore the specified scale/precision, if they are passed as parameters. 
    
    As you analyzed, the problem is the scale/precision is 0 for a int constant value, which is not right. We should fix place where scale/precision is specified wrongly.  Ignoring scale/precision and re-calcualting them in eval() means Drill has to apply that logic per input row.
    
    The reason that you saw eval() is called only once:
    Filter employee_id = 170, 
      is   employee_id = castIntDecimal28Sparse(170, scale, precision). // scale and precision is wrongly 0.
    
    Since RHS is a constant, Drill will evaluate only once, even you have multiple rows. However, this is not true, if it's not a constant expression. 
    
    To me, you point to the right cause of the problem. But we need get better place to apply the fix ( not in eval() ) method. 
    
    The place where we get scale/precision as 0 
    
    https://github.com/apache/drill/blob/master/exec/java-exec/src/main/java/org/apache/drill/exec/expr/ExpressionTreeMaterializer.java#L315-L316
    



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