How to tune self join query in Oracle 11g

Question

Oracle & SQL new to me,and I'm still in learning phase.
Could you please help me to tune below oracle query?? This table contains ~95 lac records and it takes 1 hour to retrieve data using this query.
Your suggestions/comments/help will be appreciated.
Thanks in advance.
SELECT A.CNO AS CNO, A.FNO AS FNO, A.CID AS CID, A.IID AS IID
FROM CAC_LKP A, (SELECT C_DATE, CNO, FNO
FROM (SELECT MAX(CAC_LKP.C_DATE) AS C_DATE, CAC_LKP.CNO AS CNO, CAC_LKP.FNO AS FNO
FROM CAC_LKP
WHERE ACTIVE = 'Y' GROUP BY CNO, FNO)) B
WHERE A.C_DATE = B.C_DATE
AND A.CNO = B.CNO
AND A.FNO = B.FNO
AND A.ACTIVE = 'Y'
Primary key is defied over combination of c_date,iid,active.
Edited by: 1009236 on Jun 1, 2013 12:52 AM

Answer 1

>
SELECT  A.CNO AS CNO,
        A.FNO AS FNO,
        A.CID AS CID,
        A.IID AS IID
FROM    CAC_LKP A,
                        SELECT  C_DATE,
                                CNO,
                                FNO
                        FROM
                            SELECT  MAX(CAC_LKP.C_DATE) AS C_DATE,
                                    CAC_LKP.CNO AS CNO,
                                    CAC_LKP.FNO AS FNO
                            FROM CAC_LKP
                            WHERE ACTIVE = 'Y'
                            GROUP BY CNO, FNO
                    ) B
WHERE   A.C_DATE = B.C_DATE     AND
        A.CNO = B.CNO           AND
        A.FNO = B.FNO           AND
        A.ACTIVE = 'Y';Hi,
Before even starting to see why there is a performance problem, I think you should consider the fact that there is logical problem in your WHERE clause. According to what you mentioned the primary key is composed of *(c_date, iid, active)* yet iid is absent in both the global query's WHERE clause and also that of the subquery.
Consequently the (aggregate) rows in the subquery will not be linked based on a correct logic to the external query.
Regards,
Dariyoosh