@Override
  protected PrimitiveTypeInfo deriveResultApproxTypeInfo() {
    // Hive 0.12 behavior where double / decimal -> decimal is gone.
    return TypeInfoFactory.doubleTypeInfo;
  }
Note that in SQL, the return type of divide is not necessarily the same
as the parameters. For example, 3 / 2 = 1.5, not 1. To follow SQL, we always
return a decimal for divide.
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFOPDivide.java