Query Performance problem after upgrade from 8i to 10g

Question

Following query takes longer time in 10g.
SELECT LIC_ID,FSCL_YR,KEY_NME,CRTE_TME_STMP,REMT_AMT,UNASGN_AMT,BAD_CK_IND,CSH_RCPT_PARTY_ID,csh_rcpt_id,REC_TYP,XENT_ID,CLNT_CDE,BTCH_CSH_STA,file_nbr,
lic_nbr,TAX_NBR,ASGN_AMT FROM (
SELECT /*+ FIRST_ROWS*/
     cpty.lic_id,
cpty.clnt_cde,
cpty.csh_rcpt_party_id,
cpty.csh_rcpt_id,
cpty.rec_typ,
cpty.xent_id,
cr.fscl_yr,
cbh.btch_csh_sta,
nam.key_nme,
lic.file_nbr,
lic.lic_nbr,
cr.crte_tme_stmp,
cr.remt_amt,
cr.unasgn_amt,
ee.tax_nbr,
cr.asgn_amt,
cr.bad_ck_ind
FROM lic lic
,csh_rcpt_party cpty
,name nam
,xent ee
,csh_rcpt cr
,csh_btch_hdr cbh
WHERE 1 = 1
AND ee.xent_id = nam.xent_id
AND cbh.btch_id = cr.btch_id
AND cr.csh_rcpt_id = cpty.csh_rcpt_id
AND ee.xent_id = cpty.xent_id
AND cpty.lic_id = lic.lic_id(+)
AND (cpty.clnt_cde IN ( SELECT clnt_cde
FROM clnt
               START WITH clnt_cde = '4006'
CONNECT BY PRIOR clnt_cde_prnt = clnt_cde)
OR cpty.clnt_cde IS NULL)
AND nam.cur_nme_ind = 'Y'
AND nam.ent_nme_typ = 'P' AND nam.key_nme LIKE 'WHITE%')
order by lic_id
Explain Plan in 8i
0 SELECT STATEMENT Optimizer=HINT: FIRST_ROWS (Cost=17 Card=1
Bytes=107)
1 0 FILTER
2 1 NESTED LOOPS (Cost=17 Card=1 Bytes=107)
3 2 NESTED LOOPS (Cost=15 Card=1 Bytes=101)
4 3 NESTED LOOPS (OUTER) (Cost=13 Card=1 Bytes=73)
5 4 NESTED LOOPS (Cost=11 Card=1 Bytes=60)
6 5 NESTED LOOPS (Cost=6 Card=1 Bytes=35)
7 6 INDEX (RANGE SCAN) OF 'NAME_WBSRCH1_I' (NON-UN
IQUE) (Cost=4 Card=1 Bytes=26)
8 6 TABLE ACCESS (BY INDEX ROWID) OF 'XENT' (Cost=
2 Card=4649627 Bytes=41846643)
9 8 INDEX (UNIQUE SCAN) OF 'EE_PK' (UNIQUE) (Cos
t=1 Card=4649627)
10 5 TABLE ACCESS (BY INDEX ROWID) OF 'CSH_RCPT_PARTY
' (Cost=5 Card=442076 Bytes=11051900)
11 10 INDEX (RANGE SCAN) OF 'CPTY_EE_FK_I' (NON-UNIQ
UE) (Cost=2 Card=442076)
12 4 TABLE ACCESS (BY INDEX ROWID) OF 'LIC' (Cost=2 Car
d=3254422 Bytes=42307486)
13 12 INDEX (UNIQUE SCAN) OF 'LIC_PK' (UNIQUE) (Cost=1
Card=3254422)
14 3 TABLE ACCESS (BY INDEX ROWID) OF 'CSH_RCPT' (Cost=2
Card=6811443 Bytes=190720404)
15 14 INDEX (UNIQUE SCAN) OF 'CR_PK' (UNIQUE) (Cost=1 Ca
rd=6811443)
16 2 TABLE ACCESS (BY INDEX ROWID) OF 'CSH_BTCH_HDR' (Cost=
2 Card=454314 Bytes=2725884)
17 16 INDEX (UNIQUE SCAN) OF 'CBH_PK' (UNIQUE) (Cost=1 Car
d=454314)
18 1 FILTER
19 18 CONNECT BY
20 19 INDEX (UNIQUE SCAN) OF 'CLNT_PK' (UNIQUE) (Cost=1 Ca
rd=1 Bytes=4)
21 19 TABLE ACCESS (BY USER ROWID) OF 'CLNT'
22 19 TABLE ACCESS (BY INDEX ROWID) OF 'CLNT' (Cost=2 Card
=1 Bytes=7)
23 22 INDEX (UNIQUE SCAN) OF 'CLNT_PK' (UNIQUE) (Cost=1
Card=1)
Explain Plan in 10g
0 SELECT STATEMENT Optimizer=HINT: FIRST_ROWS (Cost=19 Card=1
Bytes=112)
1 0 SORT (ORDER BY) (Cost=19 Card=1 Bytes=112)
2 1 FILTER
3 2 NESTED LOOPS (Cost=18 Card=1 Bytes=112)
4 3 NESTED LOOPS (Cost=16 Card=1 Bytes=106)
5 4 NESTED LOOPS (OUTER) (Cost=14 Card=1 Bytes=78)
6 5 NESTED LOOPS (Cost=12 Card=1 Bytes=65)
7 6 NESTED LOOPS (Cost=6 Card=1 Bytes=34)
8 7 INDEX (RANGE SCAN) OF 'NAME_WBSRCH1_I' (INDE
X) (Cost=4 Card=1 Bytes=25)
9 7 TABLE ACCESS (BY INDEX ROWID) OF 'XENT' (TAB
LE) (Cost=2 Card=1 Bytes=9)
10 9 INDEX (UNIQUE SCAN) OF 'EE_PK' (INDEX (UNI
QUE)) (Cost=1 Card=1)
11 6 TABLE ACCESS (BY INDEX ROWID) OF 'CSH_RCPT_PAR
TY' (TABLE) (Cost=6 Card=1 Bytes=31)
12 11 INDEX (RANGE SCAN) OF 'CPTY_EE_FK_I' (INDEX)
(Cost=2 Card=4)
13 5 TABLE ACCESS (BY INDEX ROWID) OF 'LIC' (TABLE) (
Cost=2 Card=1 Bytes=13)
14 13 INDEX (UNIQUE SCAN) OF 'LIC_PK' (INDEX (UNIQUE
)) (Cost=1 Card=1)
15 4 TABLE ACCESS (BY INDEX ROWID) OF 'CSH_RCPT' (TABLE
) (Cost=2 Card=1 Bytes=28)
16 15 INDEX (UNIQUE SCAN) OF 'CR_PK' (INDEX (UNIQUE))
(Cost=1 Card=1)
17 3 TABLE ACCESS (BY INDEX ROWID) OF 'CSH_BTCH_HDR' (TAB
LE) (Cost=2 Card=1 Bytes=6)
18 17 INDEX (UNIQUE SCAN) OF 'CBH_PK' (INDEX (UNIQUE)) (
Cost=1 Card=1)
19 2 FILTER
20 19 CONNECT BY (WITH FILTERING)
21 20 TABLE ACCESS (BY INDEX ROWID) OF 'CLNT' (TABLE) (C
ost=2 Card=1 Bytes=15)
22 21 INDEX (UNIQUE SCAN) OF 'CLNT_PK' (INDEX (UNIQUE)
) (Cost=1 Card=1)
23 20 NESTED LOOPS
24 23 BUFFER (SORT)
25 24 CONNECT BY PUMP
26 23 TABLE ACCESS (BY INDEX ROWID) OF 'CLNT' (TABLE)
(Cost=2 Card=1 Bytes=7)
27 26 INDEX (UNIQUE SCAN) OF 'CLNT_PK' (INDEX (UNIQU
E)) (Cost=1 Card=1)
28 20 TABLE ACCESS (FULL) OF 'CLNT' (TABLE) (Cost=5 Card
=541 Bytes=5951)
Explain plan looks different in steps 19 to 28. I am not sure why 10g have more steps

Answer 1

Hi
I have no experience in 8i. I do know 10g does costing different from 8i. So I think the other plan might got elliminated.
Normally when I see differences. I just collect statistics on the tables and the indexes and remove the hints. Hints are not good . This has helped me to solve few problems.
Thanks
CT