Query Optimization

 the query which takes about 1 min in teradata takes over 30 mins is Oracle 11.2
Platform : Linux 64bit

UPDATE sh_store_fcasts sf
SET used = 0
where exists (select '1' from promos_to_forecast rt
WHERE sf.offer_number = rt.offer_number
AND sf.base_product_number_std = rt.base_product_number_std);

Explain plan for the query is below:
   
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Plan hash value: 2782662485

---------------------------------------------------------------------------------------------------
| Id  | Operation               | Name                    | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------------
|   0 | UPDATE STATEMENT        |                         |  4940 |   173K| 12440   (1)| 00:02:30 |
|   1 |  UPDATE                 | SH_STORE_FCASTS         |       |       |            |          |
|   2 |   NESTED LOOPS          |                         |  4940 |   173K| 12440   (1)| 00:02:30 |
|   3 |    SORT UNIQUE          |                         |  4940 | 79040 |     7   (0)| 00:00:01 |
|   4 |     INDEX FAST FULL SCAN| PROMOS_TO_FORECAST_IDX1 |  4940 | 79040 |     7   (0)| 00:00:01 |
|*  5 |    INDEX RANGE SCAN     | SH_STORE_FCASTS_IDX1    |     1 |    20 |     3   (0)| 00:00:01 |