Using Bitmap Index over db link.

Question

I've a problem with the following query:
select count(*)
from TABLE_A@db_link TABLE_A, TABLE_B
where TABLE_A.ACCEPTTIME = TABLE_B.TIME_B
The above query is doing a full table scan (even after forcing index hints) on TABLE_A which has about 300M records.
TABLE_A is a local table while TABLE_B is remotely accesed using db_link.
There is a bitmap index created on the ACCEPT_TIME field of TABLE_A which is not used by the query. However when I fire this query:
Am I missing something here? How can I make the optimizer use the bitmap index on TABLE_A using remote db_link?
Here is the explain plan for the above query:
Operation     Object Name     Rows     Bytes     Cost     Object Node     In/Out     PStart     PStop
SELECT STATEMENT
Optimizer Mode=ALL_ROWS          1           2                     
SORT AGGREGATE          1      17                          
NESTED LOOPS          1      17      2                     
REMOTE     .COPY_STM     1      9      2
     STAG_PLMSPDB1.SMART.COM.PH     SERIAL          
INDEX RANGE SCAN     SYSTEM.DIM_TIME_INDX1     1      8      0                     
Regards,
Raj

Answer 1

Here is a simple case to explain the problem more clearly:
1. dept: database1 (small table dimension with 4 rows)
2. emp: database2 (large table fact with 50K rows)
3. Table emp has bitmap index on column "deptno"
4. Both tables are analyzed with defualt values using DBMS_STATS.GATHER_TABLE AND INDEX STATS
5. DB Link db2 is created from database1 to database2
Observations:
a) On Database2 when the following query is issued:
select count(*) from emp@DATABASE1 emp, dept where emp.deptno = dept.deptno
It does not use the bitmap index.
b) On Database1 when the following query is issued:
select count(*) from emp emp, dept@DATABASE2 where emp.deptno = dept.deptno
It does use the bitmap index since it is available optimizer has this information locally.
My question is how can I make use of the statistics effectively, so that the optimizer knows it has to use the bitmap index present in the remote db.
Regards,
Raj