Tài liệu Activity 6.2: Optimizing a Physical Data Design pptx

Activity 6.2: Optimizing a Physical Data Design This activity requires the use of the optimization techniques discussed in this module. You will consider ways to optimize a physical data design for insertions, updates, and deletions, as well as any nonfunctional requirements specified by the activity’s scenario. Objectives After completing this activity, you will be able to: ! Identify where data designs can potentially be optimized. ! Determine the appropriate optimization technique. Before You Begin This activity is completed individually, with a class discussion to follow. Time to complete this activity: 25 minutes 36 Activity 6.2: Optimizing a Physical Data Design Exercise 1: Determining Areas for Optimization In this exercise, you will evaluate the logical data design presented in the following illustration, and determine areas in which the physical data design could potentially be optimized. Bitmap found in file v06_1609a_act61-answer.vsd or .bmp TypeID (FK) (N)Int FirstName VChar 25 MiddleInitial VChar 2 LastName VChar 25 Address1 VChar 40 Address2 VChar 40 City VChar 30 State VChar 20 Zip VChar 10 SSN VChar 9 E-Mail VChar 50 Salary Currency BillableRate Currency EmployeeID (PK) Int Employee ClientID (FK) (N)DInt EmployeeID (FK) (N)Int JobID (FK) (N)DInt TaskID(FK) (N)DInt Date Date Expenses Currency TotalHours Float BillableHours Float Description VChar 255 TimesheetID (PK) DInt Timesheet ClientID (FK) (N)DInt TimesheetID (FK) (N)DInt Date Date Amount Currency Work Description VChar 255 InvoiceID (PK) DInt Invoice Name VChar 60 Address1 VChar 40 Address2 VChar 40 City VChar 30 State VChar 20 Zip VChar 10 ClientID (PK) DInt Client EmployeeID (FK) Int Make VChar 100 Model VChar 100 VIN VChar 30 Year Date BeginMileage Int EndMileage Int VehicleID (PK) Int Vehicle Is Issued 1 Completes 1 1 ∞ ∞∞ ∞ Is Sent To 1 0 ∞ ∞∞ ∞ 1 1 ∞ ∞∞ ∞ JobDesc VChar 255 JobID (PK) DInt Job TaskID (FK) DInt JobID (FK) DInt JobTask_Link Has Bills Time To VehicleID (FK) (N)Int MaintenanceCost Currency MaintenanceDesc VChar 255 MaintenanceDate Date MaintenanceMiles Int MaintID (PK) Int VehicleMaint Can Have 0 ∞ ∞∞ ∞ 1 1 1 ∞ ∞∞ ∞ TypeDesc VChar 255 TypeID (PK) Int EmployeeType Is Classified As 1 1 1 ∞ ∞∞ ∞ 1 1 ∞ ∞∞ ∞ ClientID(FK) DInt EmployeeID(FK) Int StartDate Date EndDate Date Description VChar 255 ContractID(PK) DInt Contract Purchases 1 1 0 ∞ ∞∞ ∞ Is Made From Contracts With TaskDesc VChar 255 TaskID (PK) DInt Task Has 1 ∞ ∞∞ ∞ 1 0 ∞ ∞∞ ∞ VehicleID (FK) Int EmployeeID(FK) Int Vehicle_Link Can Be Assigned To 0 ∞ ∞∞ ∞ 1 Bills Time To 1 ∞ ∞∞ ∞ 1 Activity 6.2: Optimizing a Physical Data Design 37 Scenario Ferguson and Bardell, Inc. has identified the following issues: 1. For ease of reporting, year-to-date (YTD) hours must be tracked for each consultant. Create a new field in the Employee Table, YTDHours Float 2. Management runs tax reports that require frequent location of employee records by Social Security number (SSN). The database administrators have noticed that running these reports drastically reduces the performance of the system during the day. You have been requested to fix this performance issue as soon as possible. Solutions can vary. Some solutions may include: Create an index on SSN field. Use SSN as the primary key for the Employee table; then store the records in SSN order. 3. Currently timesheets are queried by last name to run several reports and queries. This situation has been identified as a performance problem by the database administrators, and they are requesting a fix as soon as possible. (The field is already indexed.) Solutions can vary. Denormalize the Timesheet table to include, as duplicates from the Employee table, the FirstName, MiddleIntial, and LastName fields. Create an index on the LastName field in the Timesheet table. 4. Consultants must be able to enter timesheet information even if the rest of the system is unavailable. Solutions can vary. Solutions may include: Replicate the database on the local client computer using MSDE, and then upload the new information to the main SQL Server database daily. Create a separate database and table for the client computers that only accept timesheet data. Replicate this data to the main database as needed. 5. Management must be able to run reports even if the rest of the system is unavailable. Solutions can vary. Solutions may include: Replicate the database on the local client computer using MSDE. Create a separate reporting database that receives replicated information on a periodic basis. 6. The security of the client database is too lax. What can be done to implement a logon procedure or to ensure that only authorized users are viewing customer information? Solutions can vary. Solutions may include: Strengthen the password requirements. Implement a more secure authentication mechanism using digital certificates. 38 Activity 6.2: Optimizing a Physical Data Design ! Determine possible optimizations 1. Review the issues in the previous scenario 2. Find optimizations in the data model to resolve the issues. 3. Write these optimizations in the space provided below. Be sure to include any additional entities that might be required to resolve the issues identified by Ferguson and Bardell, Inc. Next, you will present your findings to the class. . information to the main SQL Server database daily. Create a separate database and table for the client computers that only accept timesheet data. Replicate. will evaluate the logical data design presented in the following illustration, and determine areas in which the physical data design could potentially