Best way of using two or more functions - about speed?

Question

Hello.
I would like to know what is faster.
1. If you have one function and in that function you call another function, like
fun1 is
begin
input := fun2(old_input);
return input;
end;
Call:
select fun1(input) from dual;
2. Or if you have two separate functions and call them like
select fun1(fun2(input)) from dual;
Thanks
Message was edited by:
DejanH

Answer 1

Not so scientific observation. But my func2 seems to be taking more time.
SQL> create or replace function func1
  2  return date is
  3  v_date date;
  4  begin
  5     select sysdate
  6     into v_date
  7     from dual;
  8 
  9     return v_date;
10  end;
11  /
Function created.
Elapsed: 00:00:00.02
SQL>
SQL>
SQL> create or replace function func2
  2  return date is
  3  v_date date;
  4  begin
  5     select func1
  6     into v_date
  7     from dual;
  8 
  9     return v_date;
10  end;
11  /
Function created.
Elapsed: 00:00:00.02
SQL>
SQL>
SQL> create or replace function func3
  2  return date is
  3  v_date date;
  4  begin
  5     v_date := func1;
  6  --
  7     return v_date;
  8  end;
  9  /
Function created.
Elapsed: 00:00:00.02
SQL>
SQL> create or replace function func4
  2  return date is
  3  begin
  4     return func1;
  5  end;
  6  /
Function created.
Elapsed: 00:00:00.01
SQL>
SQL> declare
  2     var_date date;
  3  begin
  4     for i in 1..10000 loop
  5        select func2
  6        into var_date
  7        from dual;
  8     end loop;
  9  end;
10  /
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.07
SQL>
SQL>
SQL>
SQL> declare
  2     var_date date;
  3  begin
  4     for i in 1..10000 loop
  5        select func3
  6        into var_date
  7        from dual;
  8     end loop;
  9  end;
10  /
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.02
SQL>
SQL>
SQL> declare
  2     var_date date;
  3  begin
  4     for i in 1..10000 loop
  5        select func4
  6        into var_date
  7        from dual;
  8     end loop;
  9  end;
10  /
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.02
SQL>
SQL>
SQL>
SQL> Cheers
Sarma.