The following table shows a sample of the data files before you repartition the data files:

Data File	Purchase Order Date	Range of Values
1	9/01/10, 11/24/10, 12/24/10, 10/15/10	9/01/10 - 12/24/10
2	12/31/10, 9/02/10, 10/31/10, 11/02/10	9/02/10 - 12/31/10
3	11/28/10, 10/05/10, 12/24/10, 9/15/10	9/15/10 - 12/24/10
4	9/30/10, 11/24/10, 10/01/10, 12/28/10	9/30/10 - 12/28/10

When you run a query to select purchase orders for 12/24/10, the query processes all data files because 12/24/10 is found in the range of all data files. The query performance is slow because the query selects a large number of data files.