Can you help me to optimize this query ( 46 min on 9.2.0.4)
thanks in advance ...

SELECT   a.mois, DBMS_UTILITY.get_hash_value (a.uga, 1, POWER (2, 30)) AS
uga,
  3           SUM (a.caxv) caxv, SUM (a.unxv * c.coepdt) unxv, SUM (a.pxv)
pxv,
  4           SUM (a.caxh) caxh, SUM (a.unxh * c.coepdt) unxh, SUM (a.pxh)
pxh,
  5           SUM (DECODE (b.caxv, NULL, 0, b.caxv)) caxv_a1, d.idmar,
  6           SUM (DECODE (b.unxv, NULL, 0, b.unxv * c.coepdt)) unxv_a1,
  7           SUM (DECODE (b.pxv, NULL, 0, b.pxv)) pxv_a1,
  8           SUM (DECODE (b.caxh, NULL, 0, b.caxh)) caxh_a1,
  9           SUM (DECODE (b.unxh, NULL, 0, b.unxh * c.coepdt)) unxh_a1,
 10           SUM (DECODE (b.pxh, NULL, 0, b.pxh)) pxh_a1
 11      FROM zwxp.job_vntxpo_uga a,
 12           zwxp.job_vntxpo_uga b,
 13           (SELECT codpdt, coepdt, idmar, amm
 14              FROM xponent_pdtmar) c,
 15           (SELECT idmar
 16              FROM xponent_mar) d
 17     WHERE a.uga = b.uga(+)
 18       AND a.codcip = b.codcip(+)
 19       AND b.codcip = c.amm(+)
 20       AND c.idmar = d.idmar(+)
 21       AND b.mois(+) = ADD_MONTHS (a.mois, -12)
 22  GROUP BY d.idmar, a.mois, a.uga
 23

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------- -------------------------

--------------------------------------------------------------------------- -------------
| Id  | Operation               |  Name                | Rows  | Bytes
|TempSpc| Cost  |
--------------------------------------------------------------------------- -------------
|   0 | SELECT STATEMENT        |                      | 65188 |  5538K|
|   710K|
|   1 |  SORT GROUP BY          |                      | 65188 |  5538K|
1343M|   710K|
|   2 |   NESTED LOOPS OUTER    |                      |    14M|  1206M|
|   303K|
|*  3 |    HASH JOIN OUTER      |                      |    14M|  1179M|
860M|   303K|
|   4 |     MERGE JOIN OUTER    |                      |    10M|   740M|
|   284K|
|   5 |      SORT JOIN          |                      |    10M|   370M|
1204M|   142K|
|   6 |       TABLE ACCESS FULL | JOB_VNTXPO_UGA       |    10M|   370M|
|  3776 |
|*  7 |      SORT JOIN          |                      |    10M|   370M|
1204M|   142K|
|   8 |       TABLE ACCESS FULL | JOB_VNTXPO_UGA       |    10M|   370M|
|  3776 |
|   9 |     INDEX FAST FULL SCAN| XPONENT_PDTMAR_IDX1  |   781 |  8591 |
|     2 |
|* 10 |    INDEX UNIQUE SCAN    | XPONENT_MAR_PK       |     1 |     2 |
|       |
--------------------------------------------------------------------------- -------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("B"."CODCIP"="XPONENT_PDTMAR"."AMM"(+))
   7 - access("A"."UGA"="B"."UGA"(+))
       filter("B"."MOIS"(+)=ADD_MONTHS("A"."MOIS",-12) AND
"A"."CODCIP"="B"."CODCIP"(+)
              AND "A"."UGA"="B"."UGA"(+))
  10 - access("XPONENT_PDTMAR"."IDMAR"="XPONENT_MAR"."IDMAR"(+))