Positional vs. named parameter passing

Question

Is named parameter passing always better than positional when calling a PL/SQL stored procedure? What are the benefits and pitfalls of each method. Are there instances where you prefer one over the other?

Answer 1

Hi Roger,
I personally prefer named notation due to its much enhanced clarity. It greatly helps a subsequent developer by not forcing him/her to look up the spec of the procedure or function each time they see it referenced in the code which calls it (I have a terrible short-term memory - so this is particularly frustrating to me).
Additionally, if some whacko comes by and changes the order (but not the names) of the parameters to the referenced procedure or function - named notation protects you from having to change your code - with positional notation - you MUST change your code.
Of course, named notation is not supported in normal SQL which calls a function, only positional is. But for PL/SQL I say use named notation all the way.
I've never tested a comparison of performance, but I would take an educated guess that it is roughly equivalent (within a few microseconds) between the approaches.
One example I think will show you the benefits of named over positional is a call to DBMS_STATS.GATHER_TABLE_STATS. This packaged procedure is used all of the time, but it has a large number of arguments. Changing a call to it can be challenging with positional notation if you don't remember the parameter order.
Here's the named notation call:
BEGIN
   DBMS_STATS.gather_table_stats (ownname               => 'SCOTT'
                                , tabname               => 'EMP'
                                , partname              => NULL
                                , estimate_percent      => DBMS_STATS.auto_sample_size
                                , block_sample          => FALSE
                                , method_opt            => 'FOR ALL INDEXED COLUMNS SIZE 254'
                                , DEGREE                => NULL
                                , granularity           => 'ALL'
                                , CASCADE               => TRUE
                                , no_invalidate         => FALSE
END;
/Here's the positional notation call:
BEGIN
   DBMS_STATS.gather_table_stats ('SCOTT'
                                , 'EMP'
                                , NULL
                                , DBMS_STATS.auto_sample_size
                                , FALSE
                                , 'FOR ALL INDEXED COLUMNS SIZE 254'
                                , NULL
                                , 'ALL'
                                , TRUE
                                , FALSE
END;
/I strongly prefer to support code with the first example over the 2nd.
Hope this helps...
Message was edited by:
PDaddy
Message was edited by:
PDaddy