Oracle PL/SQL: How to find unused variables in a long package?

Question

Please suppose you have an Oracle PL/SQL package of about 200,000 rows of code.

Is there any fast way to detect variables declared, but not used in the package?

Thank you in advance for your kind help.

EDIT (April 7th, 2014): I am using Oracle 10G.

EDIT: I am looking for a pure PL/SQL solution.

Answer 1

The following only applies to 11g R2. It looks like PL/Scope has become available in 11g R1.

You won't get information about unused variables with PLSQL_WARNINGS='ENABLE:ALL':

SQL> !cat test.sql
set serveroutput on

alter session set plsql_warnings = 'ENABLE:ALL';

create or replace procedure foo is
  v_a number;
  v_b varchar2(10);
begin
  dbms_output.put_line('hello world!');
end;
/
show errors

exec foo

SQL> @test

Session altered.


SP2-0804: Procedure created with compilation warnings

Errors for PROCEDURE FOO:

LINE/COL ERROR
-------- -----------------------------------------------------------------
1/1      PLW-05018: unit FOO omitted optional AUTHID clause; default
         value DEFINER used

hello world!

PL/SQL procedure successfully completed.

SQL>

As you can see the only reported warning is not related to the unused variables at all. Instead PL/Scope has to be used.

The following example has bee derived from Oracle 11g – Generating PL/SQL Compiler Warnings (Java style) using PL/Scope:

SQL> alter session set plscope_settings = 'identifiers:all';

Session altered.

SQL> alter procedure foo compile;

SP2-0805: Procedure altered with compilation warnings

SQL> show errors
Errors for PROCEDURE FOO:

LINE/COL ERROR
-------- -----------------------------------------------------------------
1/1      PLW-05018: unit FOO omitted optional AUTHID clause; default
         value DEFINER used

SQL> @plsql-unused-variables.sql
Enter value for name: foo
old  10:   where  object_name = upper('&name')
new  10:   where  object_name = upper('foo')
Enter value for type: procedure
old  11:   and    object_type = upper('&type')
new  11:   and    object_type = upper('procedure')

COMPILER_WARNING
--------------------------------------------------------------------------------
V_B: variable is declared but never used (line 3)
V_A: variable is declared but never used (line 2)

SQL>

The script plsql-unused-variables.sql is just a cut and paste from the blog post mentioned above. Because I found it useful I have also made the script available in Bitbucket.

Answer 2

Set your session to report all warnings:

ALTER SESSION SET PLSQL_WARNINGS='ENABLE:ALL';

then compile your code. If the compilation indicates that there are errors, as in you get something like the following:

SP2-0804: Procedure created with compilation warnings

display any errors:

SHO ERR

If you have any unreferenced variables they should be mentioned in the list of errors. Alternatively, use a tool like PL/SQL Developer which automatically shows you these errors following a compile.

Share and enjoy.

Answer 3

PL/SQL waits to allocate memory until you assign the variable, then only allocates as much storage as needed. So no need to worry about consuming memory. (Source)

So finding and fixing unused variables is just a housekeeping exercise and won't improve the performance of the package. In other words, the simplest solution would be to do nothing.

If you're worried about unused variables anyway, you might be able to find them just by parsing the package source with command-line tools such as grep, sort and uniq (especially if they follow a coding standard such as starting all variables with v_).