Commented Code

Question

I have thousand of commented code in my procedure suppose I delete all commented code and remove all dbms_output statment will it Improve performance?
Pls reply
Umesh

Answer 1

Not saying comments is a bad thing in itself. But comments in a SQL (depending on the Oracle version) can wind up in the Shared Pool. It is also can prevent a SQL from being sharable.
This is what happens in 9i when you use comments in the SQL. It winds up in the Shared Pool:
SQL> create or replace procedure fooProc is
2 i integer;
3 begin
4 select
5 /* this is comment line 1
6 line2
7 and yet another comment
8 */
9 count(*) into i
10 from user_objects;
11 end;
12 /
Procedure created.
SQL> show errors
No errors.
SQL>
SQL> exec fooProc
PL/SQL procedure successfully completed.
SQL>
SQL> select sql_text from v$sqlarea
2 where sql_text like '%user_objects';
SQL_TEXT
SELECT /* this is comment line 1 line2 and yet another comment
*/ count(*) from user_objects
SQL>
The 10g parser is more clever than this and will strip out non CBO comment hints from the SQL (and remove whitespaces and formatting) in order to "clean" the SQL and making it more uniform and thus more likely sharable with the same SQL that has been formatted differently. Here's a 10g example:
[pre]
SQL> create or replace procedure fooProc is
2 i integer;
3 begin
4 select
5 /* this is comment line 1
6 line2
7 and yet another comment
8 */
9 count(*) into i
10 from user_objects;
11 end;
12 /
Procedure created.
SQL> show errors
No errors.
SQL>
SQL> exec fooProc
PL/SQL procedure successfully completed.
SQL>
SQL> select sql_text from v$sqlarea
2 where sql_text like '%USER_OBJECTS';
SQL_TEXT
SELECT COUNT(*) FROM USER_OBJECTS
SQL>
Note - all uppercase and no comments.
It was just simply good practice to rather comment before or after a SQL in the past. Not so much relevant anymore, but lots of people still are using 9i and should note this.