Problem with Incident_date column in CS_INCIDENTS_ALL_B table

Question

Hi everyone,
I am using date range search in CS_INCIDENTS_ALL_B table using the column INCIDENT_DATE. As this is a standard table, a index is already defined there on the column INCIDENT_DATE.
If I am using the following query: [26-OCT-2010 is today's date]
SELECT *
FROM cs_incidents_all_b
WHERE incident_date BETWEEN TO_DATE ('25-OCT-2010 00:00:00',
'DD-MON-RRRR HH24:MI:SS'
AND TO_DATE ('26-OCT-2010 23:59:59',
'DD-MON-RRRR HH24:MI:SS'
the Explain plan is showing following values for Cost, Bytes and Cardinality:
Cost:4 Bytes:559 Cardinality:1
If I am running the same query for the date range '01-OCT-2010' and '02-OCT-2010'
SELECT *
FROM cs_incidents_all_b
WHERE incident_date BETWEEN TO_DATE ('01-OCT-2010 00:00:00',
'DD-MON-RRRR HH24:MI:SS'
AND TO_DATE ('02-OCT-2010 23:59:59',
'DD-MON-RRRR HH24:MI:SS'
Explain plan is showing following values - Cost:3,643 Bytes: 2,217553 and Cardinality: 3,967. [this query is taking more time compared to above one].
As per my notice, this cost is not depending on the number of rows resulting from the query. This is because, the number of rows resulted in first query (25-OCT-2010 to 26-OCT-2010) is 120 where as number of rows from second query (01-OCT-2010 and 02-OCT-2010) is only 2.
If I increase the date range such that the duration is 1 month, the cost is still increasing and Index range scan is not being used at all.
Please suggest me how can I write a query that results in a same cost and execution time for all the date ranges.
Thanks in advance,
Sam

Answer 1

In 11.5.9, the problem and resolution codes are stored in FND_LOOKUP_VALUES table with lookup type as 'REQUEST_PROBLEM_CODE' and 'REQUEST_RESOLUTION_CODE'. I'm hoping you could still use these tables to find problem codes, even if you were on 11.5.10 or R12.
Join would be something like:
WHERE fnd_lookup_values.lookup_type = 'REQUEST_PROBLEM_CODE'
AND fnd_lookup_values.problem_code = cs_incidents_all_b.problem_code
Regarding restricting the query for Depot Repair service requests, you need to restrict by the the incident_type_id for this type of SRs (like id for Depot incident type is 10003 for us).
HTH
Alka