Rewrite the max query...

Question

The inner select statement works fast and few columns generated based on A.QSN_DESC_X values, AND to get a single row I am doing a group by on cmpltn_i by taking the max row. When I do this group by the query takes approx 5 mnts. The inner query returns 227270 records. The final query give 37,000 records.
Can someone suggest any better way to write this query?
select
CMPLTN_I,
max(emp_i) as emp_i,
max(first_name) as first_name,
max(last_name) as last_name,
max (vendor) as vendor,
max (product_type) as product_type,
max (event_type) as event_type,
max (dollar_amt) as dollar_amt,
max (date_received) as date_received,
max (branch_code) as branch_code
from (
select   /*+DRIVING_SITE(A)*/   
B.CMPLTN_I,
B.emp_i, 
E.EMP_1ST_NME_X as first_name,
E.EMP_LAST_NME_X as last_name, 
case when substr(A.QSN_DESC_X,1,6) = 'Vendor' then A.CHCE_DESC_X else null end as vendor,
case when substr(A.QSN_DESC_X,1,12) = 'Product Type' then A.CHCE_DESC_X else null end  as product_type,
case when substr(A.QSN_DESC_X,1,10) = 'Event Type' then A.CHCE_DESC_X else null end as  event_type,
case when substr(A.QSN_DESC_X,1,13) = 'Dollar Amount' then A.CHCE_DESC_X else null end as  dollar_amt,
case when substr(A.QSN_DESC_X,1,13) = 'Date Received' then A.CHCE_DESC_X else null end as date_received,
case when substr(A.QSN_DESC_X,1,16) = 'Branch Wire Code' then A.CHCE_DESC_X else null end as branch_code        
from  OAT.FORM_FACT@REMOTE_AB A, OAT.FORM_CMPLTN_FACT@REMOTE_AB B, empl_info_dimn E
where  A.CMPLTN_I  =  B.CMPLTN_I
and      B.CMPLTN_C  =  'C'
and      B.app_i  = '20'
and      E.emp_i = B.emp_i
group by
CMPLTN_I

Answer 1

10g release 2.
cost based, statistics are good
without driving site hint, the response time is bad
SQL> select * from table(dbms_xplan.display);
PLAN_TABLE_OUTPUT
Plan hash value: 2770348679
| Id  | Operation              | Name                       | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     | Inst   |IN-OUT|
|   0 | SELECT STATEMENT REMOTE|                            |   922K|   139M|       |   104K  (1)| 00:20:49 |        |      |
|   1 |  SORT GROUP BY         |                            |   922K|   139M|   300M|   104K  (1)| 00:20:49 |        |      |
|*  2 |   HASH JOIN            |                            |   922K|   139M|  4976K| 71818   (2)| 00:14:22 |        |      |
|   3 |    REMOTE              | EMPL_INFO_DIMN             | 86311 |  3961K|       | 10903   (1)| 00:02:11 |      ! | R->S |
|*  4 |    HASH JOIN           |                            |   923K|    97M|       | 55274   (2)| 00:11:04 |        |      |
|*  5 |     TABLE ACCESS FULL  | FORM_RECIPIENT_CMPLTN_FACT | 24223 |   331K|       |   698   (3)| 00:00:09 | OATP0~ |      |
PLAN_TABLE_OUTPUT
|   6 |     TABLE ACCESS FULL  | FORM_RESP_FACT             |    10M|  1013M|       | 54439   (2)| 00:10:54 | OATP0~ |      |
Predicate Information (identified by operation id):
   2 - access("A1"."EMP_I"="A2"."EMP_I")
   4 - access("A3"."CMPLTN_I"="A2"."CMPLTN_I")
   5 - filter("A2"."APP_I"=20 AND "A2"."CMPLTN_I" IS NOT NULL AND "A2"."CMPLTN_C"='C')
Remote SQL Information (identified by operation id):
PLAN_TABLE_OUTPUT
   3 - SELECT /*+ USE_HASH ("A1") */ "EMP_I","EMP_LAST_NME_X","EMP_1ST_NME_X" FROM "DWCSADM"."EMPL_INFO_DIMN" "A1"
       (accessing '!' )
Note
   - fully remote statement
31 rows selected.