Performance issue with this query.

Question

Hi Experts,
This query is fetching 500 records.
SELECT
RECIPIENT_ID ,FAX_STATUS
FROM
FAX_STAGE WHERE LOWER(FAX_STATUS) like 'moved to%'
Execution Plan
| Id  | Operation                   | Name                | Rows  | Bytes | Cost (%CPU)|
|   0 | SELECT STATEMENT            |                     |   159K|    10M|  2170   (1)|
|   1 |  TABLE ACCESS BY INDEX ROWID| FAX_STAGE           |   159K|    10M|  2170   (1)|
|   2 |   INDEX RANGE SCAN          | INDX_FAX_STATUS_RAM | 28786 |       |   123   (0)|
Note
   - 'PLAN_TABLE' is old version
Statistics
          1  recursive calls
          0  db block gets
         21  consistent gets
          0  physical reads
          0  redo size
        937  bytes sent via SQL*Net to client
        375  bytes received via SQL*Net from client
          3  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         19  rows processed
Total number of records in the table.
SELECT COUNT(*) FROM FAX_STAGE--3679418
Distinct reccords are low for this column.
SELECT DISTINCT FAX_STATUS FROM FAX_STAGE;
Completed
BROKEN
Broken - New
moved to - America
MOVED to - Australia
Moved to Canada and australia
Functional based indexe on FAX_STAGE(LOWER(FAX_STATUS))
stats are upto date.
Still the cost is high
How to improve the performance of this query.
Please help me.
Thanks in advance.

Answer 1

With no heavy activity on your fax_stage table a bitmap index might do better - see  CREATE INDEX
I would try FTS (Full Table Scan) first as 6 vs. 3679418 is low cardinality for sure so using an index is not very helpful in this case (maybe too much Exadata oriented)
There's a lot of web pages where you can read: full table scans are not always evil and indexes are not always good or vice versa Ask Tom "How to avoid the full table scan"
Regards
Etbin