Why this to_date() filter slows down the query but not speed it up?

Question

This query returns results in less than a second:
SELECT *
  FROM ddms_datum
WHERE     person_id = 123456
       AND class_id IN (27, 28, 29)
       AND ts <= TO_DATE ('11/11/2011', 'mm/dd/yyyy')
ORDER BY ts;But when I added one more filter, the following one takes forever:
SELECT *
  FROM ddms_datum
WHERE     person_id = 123456
       AND class_id IN (27, 28, 29)
       AND ts <= TO_DATE ('11/11/2011', 'mm/dd/yyyy')
       AND ts >= TO_DATE ('11/4/2011', 'mm/dd/yyyy')
ORDER BY ts;Any ideas? It is a partitioned table.
Edited by: user9511515 on Nov 29, 2011 3:18 PM
Explain plan for Long running one:
PLAN_TABLE_OUTPUT
Plan hash value: 379705822
| Id  | Operation                          | Name         | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |
|   0 | SELECT STATEMENT                   |              |     1 |    64 |  4166   (1)| 00:00:50 |       |       |
|*  1 |  TABLE ACCESS BY GLOBAL INDEX ROWID| DDMS_DATUM   |     1 |    64 |  4166   (1)| 00:00:50 | ROWID | ROWID |
|*  2 |   INDEX RANGE SCAN                 | DATUM_TS_IDX |  1207 |       |    24   (0)| 00:00:01 |       |       |
Predicate Information (identified by operation id):
   1 - filter("PERSON_ID"=123456 AND ("CLASS_ID"=27 OR "CLASS_ID"=28 OR "CLASS_ID"=29))
   2 - access("TS">TO_DATE('2011-11-04 00:00:00', 'yyyy-mm-dd hh24:mi:ss') AND "TS"<=TO_DATE('2011-11-11
              00:00:00', 'yyyy-mm-dd hh24:mi:ss'))
       filter("TS">TO_DATE('2011-11-04 00:00:00', 'yyyy-mm-dd hh24:mi:ss') AND "TS"<=TO_DATE('2011-11-11
              00:00:00', 'yyyy-mm-dd hh24:mi:ss'))
18 rows selected.Explain Plan for fast sql:
PLAN_TABLE_OUTPUT
Plan hash value: 4090866632
| Id  | Operation                            | Name              | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |
|   0 | SELECT STATEMENT                     |                   |   114 |  7068 |   530   (1)| 00:00:07 |       |       |
|   1 |  PARTITION RANGE ALL                 |                   |   114 |  7068 |   530   (1)| 00:00:07 |     1 |    22 |
|   2 |   SORT ORDER BY                      |                   |   114 |  7068 |   530   (1)| 00:00:07 |       |       |
|   3 |    PARTITION LIST INLIST             |                   |   114 |  7068 |   529   (0)| 00:00:07 |KEY(I) |KEY(I) |
|*  4 |     TABLE ACCESS BY LOCAL INDEX ROWID| DDMS_DATUM        |   114 |  7068 |   529   (0)| 00:00:07 |   KEY |   KEY |
|   5 |      BITMAP CONVERSION TO ROWIDS     |                   |       |       |            |          |       |       |
|   6 |       BITMAP AND                     |                   |       |       |            |          |       |       |
|*  7 |        BITMAP INDEX SINGLE VALUE     | DATUM_PERSONID_IX |       |       |            |          |   KEY |   KEY |
|   8 |        BITMAP OR                     |                   |       |       |            |          |       |       |
|*  9 |         BITMAP INDEX SINGLE VALUE    | DATUM_CLASSID_IX  |       |       |            |          |   KEY |   KEY |
|* 10 |         BITMAP INDEX SINGLE VALUE    | DATUM_CLASSID_IX  |       |       |            |          |   KEY |   KEY |
|* 11 |         BITMAP INDEX SINGLE VALUE    | DATUM_CLASSID_IX  |       |       |            |          |   KEY |   KEY |
Predicate Information (identified by operation id):
   4 - filter("TS"<=TO_DATE('2011-11-11 00:00:00', 'yyyy-mm-dd hh24:mi:ss'))
   7 - access("PERSON_ID"=123456)
   9 - access("CLASS_ID"=27)
  10 - access("CLASS_ID"=28)
  11 - access("CLASS_ID"=29)
27 rows selected.Edited by: user9511515 on Nov 29, 2011 4:11 PM
Edited by: BluShadow on 30-Nov-2011 08:36
added {noformat}{noformat} tags to maintain formatting.  Please read {message:id=9360002} and learn to do this yourself in future.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

Answer 1

user9511515 wrote:
This query returns results in less than a second:
SELECT *
FROM ab_datum
WHERE person_id = 123456
AND class_id IN (27, 28, 29)
AND ts <= TO_DATE ('11/11/2011', 'mm/dd/yyyy')
ORDER BY ts;
But when I added one more filter, the following one takes forever:
SELECT *
FROM ab_datum
WHERE person_id = 123456
AND class_id IN (27, 28, 29)
AND ts <= TO_DATE ('11/11/2011', 'mm/dd/yyyy')
AND ts >= TO_DATE ('11/4/2011', 'mm/dd/yyyy')
ORDER BY ts;
Any ideas? It is a partitioned table.
Edited by: user9511515 on Nov 29, 2011 3:18 PMpost EXPLAIN PLAN for both SQL statements