Optimizer Not Working?

Hi,

The product uses a simple stored procedure. The query times out when there are five million records in the table. It looks like below:


DECLARE


@CreatedStatus int,

@PendingStatus int;

SELECT


@CreatedStatus = [LV].[ufGetCode]('SaleStatus', 'Created'), -- which returns 1001

@PendingStatus = [LV].[ufGetCode]('SaleStatus', 'Pending'); -- which returns 1002


SELECT *

FROM LV.Detail WITH (READPAST)

WHERE Status = @CreatedStatus OR


Status = @PendingStatus;


Status columne is non-clustered index. The query takes more than 30 seconds. But when i use the query below:

SELECT * FROM LV.Detail WITH (READPAST) WHERE Status = 1001 or Status = 1002
The query is done very fast. No time out.


Anybody knows what makes difference? I am using SQL 2005.