Query is not using the INDEX

Question

I have issue with a query as follows. It is not using index when i keep a function on the left hand side of comparison in where condition.
But when I remove the function it is using index.
With BLC AS
Name                                      Null?    Type
ID                                        NOT NULL NUMBER
MASTER_VALUE               NOT NULL NUMBER(8)
DESC_TEXT_ID                                    NUMBER
GVM                                                     VARCHAR2(50)
MASTER_LOOKUP_ID    NOT NULL  NUMBER
WORK_SECTION_ID                          NUMBER
AUDIT_TRAIL_NO                              NUMBER
SQL> SELECT COUNT(*) FROM BLC;
  COUNT(*)
      7769
SQL> SELECT COUNT(DISTINCT(GVM)) "distinct" FROM BLC;
  distinct
      1350
SQL> SELECT COUNT(*) "nulls" FROM BLC WHERE GVM IS NULL;
     nulls
      6419
SQL> SELECT COLUMN_NAME,INDEX_NAME FROM DBA_IND_COLUMNS WHERE TABLE_NAME='BLC';
COLUMN_NAME                              INDEX_NAME
MASTER_LOOKUP_ID      LKPCDE_MSTLKP_FK_I
WORK_SECTION_ID        LKPCDE_WRKSEC_FK_I
GVM                                   LKPCDE_UK
MASTER_VALUE              LKPCDE_MASTERID_VALUE_UK
MASTER_LOOKUP_ID     LKPCDE_MASTERID_VALUE_UK
ID                                       LKPCDE_PK
SQL> EXPLAIN PLAN FOR SELECT ID FROM BLC WHERE UPPER ( GVM) = 'MAIN_ORG';
Explained.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value: 3196655606
| Id  | Operation         | Name             | Rows  | Bytes | Cost (%CPU)| Time|
PLAN_TABLE_OUTPUT
|   0 | SELECT STATEMENT  |                  |    78 |   624 |    18   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| BLC |    78 |   624 |    18   (0)| 00:00:01 |
Predicate Information (identified by operation id):
PLAN_TABLE_OUTPUT
   1 - filter(UPPER("GVM")='MAIN_ORG')
13 rows selected.
SQL> EXPLAIN PLAN FOR SELECT ID FROM BLC WHERE GVM
  = 'MAIN_ORG';
Explained.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value: 1620245961
| Id  | Operation                   | Name             | Rows  | Bytes | Cost (%
CPU)| Time     |
PLAN_TABLE_OUTPUT
|   0 | SELECT STATEMENT            |                  |     1 |     8 |     2
(0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| BLC |     1 |     8 |     2
(0)| 00:00:01 |
|*  2 |   INDEX UNIQUE SCAN         | LKPCDE_UK        |     1 |       |     1
(0)| 00:00:01 |
PLAN_TABLE_OUTPUT
Predicate Information (identified by operation id):
   2 - access("GVM"='MAIN_ORG')
14 rows selected.
SQL> EXPLAIN PLAN FOR SELECT /* INDEX(LKPCDE_UK) */ ID FROM BLC WHE
RE UPPER ( GVM ) = 'MAIN_ORG';
Explained.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value: 3196655606
| Id  | Operation         | Name             | Rows  | Bytes | Cost (%CPU)| Time
     |
PLAN_TABLE_OUTPUT
|   0 | SELECT STATEMENT  |                  |    78 |   624 |    18   (0)| 00:0
0:01 |
|*  1 |  TABLE ACCESS FULL| BLC |    78 |   624 |    18   (0)| 00:0
0:01 |
Predicate Information (identified by operation id):
PLAN_TABLE_OUTPUT
   1 - filter(UPPER("GVM")='MAIN_ORG')
13 rows selected.
Please let me know how i can force to use an index as it is causing CPU usage.
I can not change the query in application as it is used at many places.
Thanks

Answer 1

Hi,
Version is
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi
PL/SQL Release 10.2.0.5.0 - Production
CORE    10.2.0.5.0      Production
TNS for 64-bit Windows: Version 10.2.0.5.0 - Production
NLSRTL Version 10.2.0.5.0 - Production
Sorry, in my last post i forgot to mention that i already created a function based index but still it is not using because, there is a UNIQUE constraint on that column.
Thanks