Department of Computer Science csi481 Database Systems Lab 8 – Distributed Databases Exercises



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Department of Computer Science

CSI481 Database Systems

Lab 8
– Distributed Databases Exercises



1. Distributed System Architecture Exercise A multinational engineering company has decided to distribute its project management information at the regional level in mainland Britain. The current centralized relational schema is as follows Employee (NIN, fName, lName, address, DOB, sex, salary, taxCode, deptNo) Department (deptNo, deptName, managerNIN, businessAreaNo, regionNo) Project (projNo, projName, contractPrice, projectManagerNIN, deptNo)
WorksOn (NIN, projNo, hoursWorked) Business (businessAreaNo, businessAreaName) Region (regionNo, regionName) where Employee contains employee details and the national insurance number NIN is the key. Departments are grouped regionally as follows Region 1: Scotland Region 2: Wales Region 3: England Information is required by business area which covers Software Engineering, Mechanical Engineering and Electrical Engineering. There is no Software Engineering in Wales and all Electrical Engineering departments are in England. Projects are staffed by local department offices.

Page 2 of 2 As well as distributing the data regionally, there is an additional requirement to access the employee data either by personal information (by Personnel) or by work related information (by Payroll. Draw a diagram to represent a suitable distributed architecture for this system.
2. Explain what is meant by a Distributed Database System and discuss the motivation in providing such a system.
3. Compare and contrast a Distributed Database with distributed processing. Under what circumstances would you choose a Distributed Database over distributed processing
4. What is the difference between a homogeneous and heterogeneous DDBMS? Under what circumstances would such systems generally arise
5. What functionality do you expect in a distributed DBMS
6. What are the strategic objectives for the definition and allocation of fragments
7. What layers of transparency should be provided with a DDBMS? Give examples to illustrate your answer. Justify your answer.
8. A DDBMS must ensure that no two sites create a database object with the same name. One solution to this problem is to create a central name server. What are the disadvantages with this approach Propose an alternative approach that overcomes these disadvantages.


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