* Certain optimizations should not be applied if UDF is not deterministic.
* Deterministic UDF returns same result each time it is invoked with a
* particular input. This determinism just needs to hold within the context of
* a query.
* @return true if the UDF is deterministic
boolean deterministic() default true;
Based on the definition o UDFType, when Hive UDF's children are non-deterministic, Hive UDF is also non-deterministic.