Query tuning to force pratition range scan

Question

Hi All,
I am working on a query that fetches data from a partitioned table, but does not use partitions. Below is the query and its explain plan.
SELECT L1_ABBREVIATION "CHARGE_LEVEL_1",
L2_ABBREVIATION "CHARGE_LEVEL_2",
L4_ABBREVIATION "CHARGE_LEVEL_4",
CUSTOMER_TYPE,
INVOICE_TEXT,
DECODE(B_PARTY_NAME, 'SSG/Default/5', 'PTW', 'NON-PTW') B_PARTY_NAME,
SUM(NUM_OF_CHARGES) "NUMBER_OF_CHARGES",
SUM(CHARGE_AMOUNT) "CHARGE_AMOUNT",
COUNT(DISTINCT PRIME_ACCOUNT_ID) "NUM_ACTIVE_USERS"
FROM TACT_PC24
WHERE START_DATE >= TRUNC(SYSDATE) + -16
AND START_DATE <= TRUNC(SYSDATE) + -10
AND 1 = 1
And ((source_system_id =
(select source_system_id
from tact_source_system
where ACCOUNT_NUMBER_PREFIX = '92')) OR ('%' = '92'))
GROUP BY L1_ABBREVIATION,
L2_ABBREVIATION,
L4_ABBREVIATION,
CUSTOMER_TYPE,
INVOICE_TEXT,
DECODE(B_PARTY_NAME, 'SSG/Default/5', 'PTW', 'NON-PTW')
Operation                                        Object               Cost     Mbytes     Partition end
SELECT STATEMENT CHOOSE Cost=3448222                              3448222          
SORT GROUP BY                                                  3448222     2193     
FILTER                     
PARTITION RANGE ITERATOR                                                            (KEY:KEY)
PARTITION LIST ALL                                                                 (1:2)
TABLE ACCESS FULL                    TACT_PC24_NEW          3267962     2193     (KEY:KEY)
TABLE ACCESS FULL               TACT_SOURCE_SYSTEM     2          0     
However when i tried below query (just hot-coded the date range values)
SELECT L1_ABBREVIATION "CHARGE_LEVEL_1",
L2_ABBREVIATION "CHARGE_LEVEL_2",
L4_ABBREVIATION "CHARGE_LEVEL_4",
CUSTOMER_TYPE,
INVOICE_TEXT,
DECODE(B_PARTY_NAME, 'SSG/Default/5', 'PTW', 'NON-PTW') B_PARTY_NAME,
SUM(NUM_OF_CHARGES) "NUMBER_OF_CHARGES",
SUM(CHARGE_AMOUNT) "CHARGE_AMOUNT",
COUNT(DISTINCT PRIME_ACCOUNT_ID) "NUM_ACTIVE_USERS"
FROM TACT_PC24
WHERE START_DATE >= to_date('20120214' ,'YYYYMMDD')
AND START_DATE <= to_date('20120220' ,'YYYYMMDD')
AND 1 = 1
And ((source_system_id =
(select source_system_id
from tact_source_system
where ACCOUNT_NUMBER_PREFIX = '92')) OR ('%' = '92'))
GROUP BY L1_ABBREVIATION,
L2_ABBREVIATION,
L4_ABBREVIATION,
CUSTOMER_TYPE,
INVOICE_TEXT,
DECODE(B_PARTY_NAME, 'SSG/Default/5', 'PTW', 'NON-PTW')
Operation                                        Object               Cost     Mbytes     Partition end
SELECT STATEMENT CHOOSE Cost=3448222                              124347
SORT GROUP BY                                                  124347 2193     
FILTER                     
PARTITION RANGE ITERATOR                                                            (KEY:KEY)
PARTITION LIST ALL                                                                 (1:2)
TABLE ACCESS FULL                    TACT_PC24_NEW          66151 2193     (KEY:KEY)
TABLE ACCESS FULL               TACT_SOURCE_SYSTEM     2          1     
Can you help me understand why explain plan varied between these queries. I would appropriate if some one can give me an approach to tune this query.

Answer 1

WHERE START_DATE >= TRUNC(SYSDATE) + -16
AND START_DATE <= TRUNC(SYSDATE) + -10
and
WHERE START_DATE >= to_date('20120214' ,'YYYYMMDD')
AND START_DATE <= to_date('20120220' ,'YYYYMMDD')
Is the same...
You got some strange conditions:
1 = 1 --> always TRUE
OR ('%' = '92') --> always FALSE
            source_system_id =
                SELECT source_system_id
                FROM tact_source_system
                WHERE ACCOUNT_NUMBER_PREFIX = '92'
            OR ('%' = '92')
-- try left join insted...