SQL queries !! Guru's please help !!

Question

Guys,
I've tried my best to tune the query but i still takes whopping 1 hour to complete. I am currently on 9.2.0.7 and PROMOTION_HISTORY tables doesn't run using parallelism. Hence i've forced it to use FULL table scan with parallel degree.
There are indexes created on for both CU10 and CV01 table but the response time is still quite high. CU10 has 56 million , CV01 has 50 million and Promotion_history has 10 million records.
I know there are Guru's out there, who probably think that the SQL can be better written ? If so, please can you suggest a better way of writing this ?
I am posting your the explain as well. ( Any suggestion on how to format the message to use different fonts ?? I don't see any option apart from Bold,italics and Underline )
SELECT /*+ FULL (B) PARALLEL(B 8) */
a.cust_brand_c, a.country_iso3_c, a.cucon_direction_c,
a.cucon_treat_typ_c, a.cucon_concern_c, a.cucon_value_trk_c,
SUBSTR (a.cucon_sys_cntct_c, 1, 10), a.cucon_cntct_trk_c,
a.cucon_action_c, a.make_c, a.model_c,
TO_CHAR (a.cucon_cntct_st_s, 'YYYY'),
TO_CHAR (a.cucon_cntct_st_s, 'MM'),
TO_CHAR (a.cucon_cntct_st_s, 'WW'), ' ', 'PROMOTED_SALES',
COUNT (DISTINCT a.xcm_consumer_pk), COUNT (DISTINCT c.vin_id_c),
SYSDATE
FROM (SELECT /*+ INDEX(VO01 XCM_VO01_VEHOFINT_IDX001) */
cu10.xcm_consumer_pk, cu10.cust_brand_c, cu10.country_iso3_c,
cu10.cucon_cntct_st_s, cu10.cucon_direction_c,
cu10.cucon_treat_typ_c, cu10.cucon_concern_c,
cu10.cucon_value_trk_c, cu10.cucon_sys_cntct_c,
cu10.cucon_cntct_trk_c, cu10.cucon_action_c, vo01.make_c,
vo01.model_c
FROM xcm_cu10_contact cu10, xcm_vo01_vehofint vo01
WHERE cu10.xcm_consumer_pk = vo01.xcm_consumer_pk(+)
AND cu10.country_iso3_c = SUBSTR (vo01.xcm_consumer_pk(+), 12, 3)
AND cu10.cucon_cntct_st_s = vo01.cucon_cntct_st_s(+)
AND cu10.cucon_cntct_r = vo01.cucon_cntct_r(+)
AND cu10.cucon_cntct_st_s > ADD_MONTHS (SYSDATE, -12)) a,
promotion_history b,
xcm_cv01_cons_veh c
WHERE a.country_iso3_c = c.country_iso3_c
AND a.cucon_cntct_st_s BETWEEN '01-jan-2004' AND '18-sep-2005'
AND a.cucon_cntct_st_s BETWEEN b.extract_date AND b.extract_date + 183
AND b.treat_type_trk_cd != 'CONTROL'
AND a.xcm_consumer_pk = b.recipient_id
AND a.xcm_consumer_pk = c.xcm_consumer_pk
AND c.cveh_link_start_y BETWEEN a.cucon_cntct_st_s
AND a.cucon_cntct_st_s + 183
AND c.vin_type_c = 'A'
GROUP BY a.cust_brand_c,
a.country_iso3_c,
a.cucon_direction_c,
a.cucon_treat_typ_c,
a.cucon_concern_c,
a.cucon_value_trk_c,
SUBSTR (a.cucon_sys_cntct_c, 1, 10),
a.cucon_cntct_trk_c,
a.cucon_action_c,
a.make_c,
a.model_c,
TO_CHAR (a.cucon_cntct_st_s, 'YYYY'),
TO_CHAR (a.cucon_cntct_st_s, 'MM'),
TO_CHAR (a.cucon_cntct_st_s, 'WW');

Answer 1

Explain plan
| Id | Operation | Name | Rows | Bytes | Cost | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |
| 0 | SELECT STATEMENT | | 1 | 200 | 1804 | | | | | |
| 1 | SORT GROUP BY | | 1 | 200 | 1804 | | | | | |
|* 2 | FILTER | | | | | | | | | |
| 3 | TABLE ACCESS BY LOCAL INDEX ROWID | XCM_CV01_CONS_VEH | 1 | 47 | 2 | | | 54,01 | PCWC | |
| 4 | NESTED LOOPS | | 1 | 200 | 1779 | | | 54,01 | P->S | QC (RAND) |
| 5 | NESTED LOOPS OUTER | | 1 | 153 | 1778 | | | 54,01 | PCWP | |
|* 6 | HASH JOIN | | 1 | 116 | 1777 | | | 54,01 | PCWP | |
| 7 | PARTITION RANGE ALL | | | | | 1 | 8 | 54,01 | PCWP | |
| 8 | TABLE ACCESS BY LOCAL INDEX ROWID| XCM_CU10_CONTACT | 29 | 2523 | 3 | 1 | 8 | 54,00 | P->P | BROADCAST |
|* 9 | INDEX RANGE SCAN | XCM_CU10_IDX_001 | 52 | | 2 | 1 | 8 | 54,00 | PCWP | |
|* 10 | TABLE ACCESS FULL | PROMOTION_HISTORY | 56099 | 1588K| 1774 | | | 54,01 | PCWP | |
| 11 | TABLE ACCESS BY INDEX ROWID | XCM_VO01_VEHOFINT | 1 | 37 | 3 | | | 54,01 | PCWP | |
|* 12 | INDEX RANGE SCAN | XCM_VO01_VEHOFINT_IDX001 | 1 | | 2 | | | 54,01 | PCWP | |
| 13 | PARTITION RANGE ITERATOR | | | | | KEY | KEY | 54,01 | PCWP | |
|* 14 | INDEX RANGE SCAN | XCM_CV01_CONS_VEH_IDX_TMP | 1 | | 1 | KEY | KEY | 54,01 | PCWP | |