Using a function return in an "IN" statement

Question

All,
I need to filter the records in a table based on the return value of a function. The function determines a person's group and then executes 2 separate select statements depending on the group.
CREATE OR REPLACE PACKAGE pkg_rolebased
AS
CURSOR all_dmn_cur
IS
SELECT dmn_id
FROM tomwojeck.pa_domain ;
CURSOR child_dmn_cur (role_id_in IN varchar)
IS
SELECT distinct r.dmn_id
FROM tomwojeck.pa_domain_restriction_domain r
WHERE r.dmn_restriction_id IN (
SELECT DISTINCT a.dmn_restriction_id
FROM tomwojeck.pa_role_wf_entity_fct_access a
WHERE a.role_id = role_id_in
                    AND a.workflow_entity_fct_id= 'View Student.Student.View'
                    AND a.dmn_restriction_id IS NOT NULL);
FUNCTION rolelookup (stud_email IN varchar)
RETURN roletable;
END;CREATE OR REPLACE PACKAGE BODY pkg_rolebased
IS
FUNCTION rolelookup (stud_email IN varchar)
RETURN roletable
IS
v_roleid varchar2(200);
v_returnval varchar2(200);
v_data roletable := roletable ();
dmn_rec all_dmn_cur%ROWTYPE;
BEGIN
-- Find out the role of the person
SELECT r.role_id
INTO v_roleid
FROM tomwojeck.pa_user_prfl p, tomwojeck.pa_user_prfl_role r
WHERE p.user_name = r.user_name
AND UPPER (p.email_addr) = UPPER (stud_email);
IF UPPER (v_roleid) = 'ALL'
THEN
OPEN all_dmn_cur;
LOOP
FETCH all_dmn_cur
INTO dmn_rec;
v_data.EXTEND;
v_data (v_data.COUNT) := dmn_rec.dmn_id;
EXIT WHEN all_dmn_cur%NOTFOUND;
END LOOP;
CLOSE all_dmn_cur;
ELSE
OPEN child_dmn_cur (v_roleid);
LOOP
FETCH child_dmn_cur
INTO dmn_rec;
v_data.EXTEND;
v_data (v_data.COUNT) := dmn_rec.dmn_id;
EXIT WHEN child_dmn_cur%NOTFOUND;
END LOOP;
CLOSE child_dmn_cur;
END IF;
RETURN v_data;
END rolelookup;
END;
The select statement to filter on this mess is:
select
lname,
fname,
dmn_id,
stud_id
from tomwojeck.pa_student p
where p.DMN_ID in (select * from table(cast(tomwojeck.pkg_rolebased.rolelookup('[email protected]') as tomwojeck.RoleTable)))
The problemm is this performs horribly! If I enter an email address that causes the first cursor to be used, it runs well, but if I use an email address that causes the second cursor to run, it takes forever.
Is there a better way to do this?
Thanks,
Tom Wojeck

Answer 1

<<The version of Oracle is 9i.>>
Could you specify the exact version? For example, 9.2.0.3.0.
<<I'm not sure of the query optimizer version. How do I find that?>>
SQL> show parameter optimizer_mode
NAME                                 TYPE
VALUE
optimizer_mode                       string
CHOOSE<<The interestin thing is that the function itself runs well; it's when I try to use the function as an "IN" clause that the performance degrades. It almost seems as though the database is retrieving each row from the student table, and then running the function to see if there are any matches. >>
Your query has to be tuned. The execution plan as well as the information on the indexes will certainly help.