Performance issue view with DENSE_RANK() in oracle - oracle

Question

We have a requirement to get the records from the below tables with mentioned matching condition & limit the count of UNIQUE COL3 to 20K.
We have achieved this by using DENSE_RANK() logic but we observed extremely slowness in performance when we have implemented in live system.
For processing 20K UNIQUE COL3 & 60K total records, it is taking 14-15 hours to complete (The process is running over a daily JOB & select FROM view & performing DML operation to few tables based on View records).
SELECT COUNT (distinct COL3) CNT1,COUNT(1) CNT2 FROM VW_ENTP;
--20,000 60,000
Without the DENSE_RAN() logic it is finishing very fast but with DENSE_RAN() it extremely slow.
Request your help to share any recommendation to IMPROVE QUERY PERFORMANCE or any alternative approach. Thanks in advance !
Sample View Code
CREATE OR REPLACE VIEW VW_ENTP(COL1, COL2, COL3, COL4, COL5, COL6, COL7, COL8, COL9, COL10) AS
SELECT
COL1, COL2, COL3, COL4, COL5, COL6, COL7, COL8, COL9, COL10
FROM
(
SELECT
NP.NFCD COL1,
D.CLO2 COL2,
NP.COL3 COL3,
E.COL4 COL4,
EDT.COL5,
EDT.COL6,
NP. COL7,
NP. COL8,
EDT.COL9 COL9,
NP.COL10,
DENSE_RANK() OVER (ORDER BY NP.COL3) RANK
FROM ENP NP,EDTS EDT,EM E,EDT D,BDT BD
WHERE EDT.COL2=D.COL2
AND E.COL3=NP.COL3
AND E.COL7=NP.COL7
AND E.COL8=NP.COL8
AND E.APP=NP.APP
AND NP.STATUS='P'
AND NP.NFCD=D.COL1
AND E.SUSP !='YES'
AND NP.APP='EDOC'
AND TRUNC(NP.RC_DATE)<=TRUNC(BD.LAST_RUN_DATE)
)
WHERE RANK<=20000;
Note : The above used columns are indexed.

Answer 1

Generally if any join condition is missed it leads to poor performance. Also you're joining few other tables and any of the tables can be causing the performance issue. Suggestion for them can be given only after having look at those tables.
To confirm if dense rank is causing the issue, you can remove it and execute the select statement. If it takes less time, then you can conclude dense rank is causing the issue. But I highly suspect it'll happen.

Answer 2

You can achieve this by row_number() function only:
CREATE OR REPLACE VIEW VW_ENTP(COL1, COL2, COL3, COL4, COL5, COL6, COL7, COL8, COL9, COL10) AS
SELECT
COL1, COL2, COL3, COL4, COL5, COL6, COL7, COL8, COL9, COL10
FROM
(select a.*, row_number() over (order by col3) rn from (
SELECT
NP.NFCD COL1,
D.CLO2 COL2,
NP.COL3 COL3,
E.COL4 COL4,
EDT.COL5,
EDT.COL6,
NP. COL7,
NP. COL8,
EDT.COL9 COL9,
NP.COL10,
row_number() OVER (partition by np.col3 ORDER BY NP.COL3) RANK
FROM ENP NP,EDTS EDT,EM E,EDT D,BDT BD
WHERE EDT.COL2=D.COL2
AND E.COL3=NP.COL3
AND E.COL7=NP.COL7
AND E.COL8=NP.COL8
AND E.APP=NP.APP
AND NP.STATUS='P'
AND NP.NFCD=D.COL1
AND E.SUSP !='YES'
AND NP.APP='EDOC'
AND TRUNC(NP.RC_DATE)<=TRUNC(BD.LAST_RUN_DATE)
) a where rank > 1 and rank <= 20000)
;
Current Query results :
COL3 RANK
1 1
2 1
3 1
3 2
3 3
3 4
4 1
5 1
Requirement :
COL3 RANK
1 1
2 2
3 3
3 3
3 3
3 3
4 4
5 5