Simple query but not using index..please help??

Question

I do have this column indexed. Why my query is not using this index?
Any help .
select count(*) from v_dis_sub_har;
SQL>
  COUNT(*)
   4543289
1 row selected.
SQL>
select vzw_vendor_id , count(*)
from v_dis_sub_har
group by vzw_vendor_id
SQL>   2    3    4 
VZW_VENDOR_ID   COUNT(*)
       200091     908653
       200013     908659
       200012     908659
       200057     908659
       200031     908659
5 rows selected.
SQL> SQL>
explain plan for
select
event_seq
from v_dis_sub_har b 
where b.VZW_VENDOR_ID='200013'
-- and b.status='P' and b.extract_date is null
SQL>   2    3    4    5    6    7 
Explained.
SQL> SQL>
select plan_table_output from table(dbms_xplan.display)
SQL> SQL>   2 
PLAN_TABLE_OUTPUT
Plan hash value: 2852398983
| Id  | Operation         | Name          | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT  |               |   908K|  7986K|  3132  (16)| 00:00:38 |
|*  1 |  TABLE ACCESS FULL| V_DIS_SUB_HAR |   908K|  7986K|  3132  (16)| 00:00:38 |
Predicate Information (identified by operation id):
PLAN_TABLE_OUTPUT
   1 - filter("B"."VZW_VENDOR_ID"=200013)
13 rows selected.
SQL> SQL>

Answer 1

You are right Justin. Oracle is not stupid as you may want to say some times when things do not happen according to you. I just created a bitmap index on status field and look what appened. Som times it uses bitmap index and some times it does not. And the reason is clear. Row count by status. 'S' status uses bitmap index where 'P' does not.
Thanks for your help.
select   status, count(*)
from v_dis_sub_har
group  by status
;SQL>   2    3    4 
S   COUNT(*)
A    5844982
P    2312759
S      20178
3 rows selected.
SQL>
explain plan for
select
event_seq
from v_dis_sub_har b 
where
--b.VZW_VENDOR_ID=200013
--  and
b.status='S'
--and b.extract_date is null
select plan_table_output from table(dbms_xplan.display)
SQL>   2    3    4    5    6    7    8    9   10 
Explained.
SQL> SQL> SQL> SQL>   2 
PLAN_TABLE_OUTPUT
Plan hash value: 829738689
| Id  | Operation                    | Name                         | Rows  | Bytes | Cost (%CPU)| T
ime     |
PLAN_TABLE_OUTPUT
|   0 | SELECT STATEMENT             |                              | 20290 |   118K|  2772   (1)| 0
0:00:34 |
|   1 |  TABLE ACCESS BY INDEX ROWID | V_DIS_SUB_HAR                | 20290 |   118K|  2772   (1)| 0
0:00:34 |
|   2 |   BITMAP CONVERSION TO ROWIDS|                              |       |       |            |
        |
|*  3 |    BITMAP INDEX SINGLE VALUE | V_DISPATCH_SUBSCRIPTION_NDX2 |       |       |            |
        |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   3 - access("B"."STATUS"='S')
15 rows selected.
SQL> SQL> set line 120
SQL> /
PLAN_TABLE_OUTPUT
Plan hash value: 829738689
| Id  | Operation                    | Name                         | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT             |                              | 20290 |   118K|  2772   (1)| 00:00:34 |
|   1 |  TABLE ACCESS BY INDEX ROWID | V_DIS_SUB_HAR                | 20290 |   118K|  2772   (1)| 00:00:34 |
|   2 |   BITMAP CONVERSION TO ROWIDS|                              |       |       |            |          |
|*  3 |    BITMAP INDEX SINGLE VALUE | V_DISPATCH_SUBSCRIPTION_NDX2 |       |       |            |          |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   3 - access("B"."STATUS"='S')
15 rows selected.
SQL>
explain plan for
select
event_seq
from v_dis_sub_har b 
where
--b.VZW_VENDOR_ID=200013
--  and
b.status='P'
--and b.extract_date is null
select plan_table_output from table(dbms_xplan.display)
      SQL>   2    3    4    5    6    7    8    9   10 
Explained.
SQL> SQL> SQL> SQL>   2 
PLAN_TABLE_OUTPUT
Plan hash value: 2852398983
| Id  | Operation         | Name          | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT  |               |  2325K|    13M|  5784  (18)| 00:01:10 |
|*  1 |  TABLE ACCESS FULL| V_DIS_SUB_HAR |  2325K|    13M|  5784  (18)| 00:01:10 |
Predicate Information (identified by operation id):
PLAN_TABLE_OUTPUT
   1 - filter("B"."STATUS"='P')
13 rows selected.
SQL>