Can any one explain why index is not used ???

Thanks



17:17:13 SQL> set autotrace off
17:17:22 SQL> l
1* select count(*) from SSRFACC_NAME
17:17:24 SQL> /

COUNT(*)
---------
252607

17:17:25 SQL> select count(*) from SSRFACC_NAME where accnt_type='T';

COUNT(*)
---------
19

17:17:46 SQL> CREATE bitmap INDEX MAGTAC.SSFRACC_NAME_ACCNTTYPE_BIDX ON MAGTAC.SSRFACC_NAME (ACCNT_T
YPE)
17:17:59 2 tablespace indx;

Index created.

17:18:07 SQL> analyze table ssrfacc_name compute statistics;

Table analyzed.

17:20:22 SQL> analyze table ssrfacc_name compute statistics for all indexes;

Table analyzed.

17:21:04 SQL> SELECT /*+ INDEX(SSFRACC_NAME_ACCNTTYPE_BIDX) */ (anal_a2), a2_name
17:21:33 2 FROM
17:21:33 3 ssrfacc_name a
17:21:33 4 WHERE accnt_type ='T'

17:21:39 SQL> set autotrace trace
17:21:45 SQL> SELECT /*+ INDEX(SSFRACC_NAME_ACCNTTYPE_BIDX) */ (anal_a2), a2_name
17:21:46 2 FROM
17:21:46 3 ssrfacc_name a
17:21:46 4 WHERE accnt_type ='T';

19 rows selected.


Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1917 Card=36087 Byte
s=1515654)

1 0 TABLE ACCESS (FULL) OF 'SSRFACC_NAME' (Cost=1917 Card=3608
7 Bytes=1515654)





Statistics
----------------------------------------------------------
0 recursive calls
5 db block gets
12630 consistent gets
11835 physical reads
0 redo size
1161 bytes sent via SQL*Net to client
660 bytes received via SQL*Net from client
5 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
19 rows processed

17:21:51 SQL>