protected PrimitiveTypeInfo deriveResultExactTypeInfoAnsiSql() {
    // No type promotion. Everything goes to decimal.
    return deriveResultDecimalTypeInfo();
  }
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