A database has been created based on the physical data model in Figure 3.2, and we find that we frequently need to find Customer records based on their telephone number. What changes need to be made to provide a higher level of performance?

Customer **CustomerIdentifier Customer TelephoneNumber CustomerName CustomerStreetAddress CustomerCity CustomerState CustomerZipCode CustomerCredit Rating CustPreferredCredit Card Order **OrderNumber Customeridentifer Ordered Item **OrderNumber **ItemNumber OrderDate Shipping Street Address Shipping City Shipping State Credit Card **Customer Credit CardNumber Customer Credit CardName Advertised Item **ItemNumber ItemDescription ItemDepartment Item Weight ItemColor ItemPrice LowestPrice LowestPriceSupplier QuantityOrdered Selling Price ItemShipping Date ShippingZipCode CustomerCredit CardNumber OrderShippingDate Order TotalCost CustomerIdentifier PreferredOption FIGURE 3.2 The physical data model. Supplier **SupplierID Supplier Name Supplier Street Address SupplierCity Supplier State Supplier ZipCode Restock_Item **SupplierID **ItemNumber ReorderPrice