Sql query is taking more time

Question

Hi all,
db:oracle 9i
I am facing below query prob.
prob is that query is taking more time 45 min than earliar (10 sec).
please any one suggest me .....
SQL> SELECT MAX (tdar1.ID) ID, tdar1.request_id, tdar1.lolm_transaction_id,
2 tdar1.transaction_version
3 FROM transaction_data_arc tdar1
4 WHERE tdar1.transaction_name ='O96U '
5 AND tdar1.transaction_type = 'REQUEST'
6 AND tdar1.message_type_code ='PCN'
7 AND NOT EXISTS (
8 SELECT NULL
9 FROM transaction_data_arc tdar2
10 WHERE tdar2.request_id = tdar1.request_id
11 AND tdar2.lolm_transaction_id != tdar1.lolm_transaction_id
12 AND tdar2.ID > tdar1.ID)
13 GROUP BY tdar1.request_id,
14 tdar1.lolm_transaction_id,
15 tdar1.transaction_version;
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=17 Card=1 Bytes=42)
1 0 SORT (GROUP BY) (Cost=12 Card=1 Bytes=42)
2 1 FILTER
3 2 TABLE ACCESS (BY INDEX ROWID) OF 'TRANSACTION_DATA_ARC
' (Cost=1 Card=1 Bytes=42)
4 3 INDEX (RANGE SCAN) OF 'NK_TDAR_2' (NON-UNIQUE) (Cost
=3 Card=1)
5 2 TABLE ACCESS (BY INDEX ROWID) OF 'TRANSACTION_DATA_ARC
' (Cost=5 Card=918 Bytes=20196)
6 5 INDEX (RANGE SCAN) OF 'NK_TDAR_7' (NON-UNIQUE) (Cost
=8 Card=4760)

Answer 1

prob is that query is taking more time 45 min than earliar (10 sec).Then something must have changed (data growth/stale statistics/...?).
You should post as much details as possible, how and what it is described in the FAQ, see:
*3. How to improve the performance of my query? / My query is running slow*.
When your query takes too long...
How to post a SQL statement tuning request
SQL and PL/SQL FAQ
Also, given your database version, using NOT IN instead of NOT EXISTS might make a difference (but they're not the same).
See: SQL and PL/SQL FAQ