Flink UDF Scalar Function called only once for all rows of select SQL in case of no parameter passed

[shamit jain]

Hi,

I am facing an issue where scalar UDF called once in case if no parameter 
passed as given below:-

public class DateTimeToEpochUDF extends ScalarFunction {
public Long eval() {
                System.out.print("Test");
                return Instant.now().toEpochMilli(); 
        }
}

Now if I run the below query I will get the same time, looks like the function 
is called only one time, as the SOP also not printed.

select DateTimeToEpochUDF(), employee_ID from Employee;

Please note if I passed the parameter in UDF like primary key it is called 
separately for each record of employee.

Request you to please let me know if I am doing something wrong.

regards,
Shamit Jain