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.