UNIVERSITY EXAMINATIONS: 2018/2019
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE IN INFORMATION
TECHNOLOGY/ BACHELOR OF BUSINESS INFORMATION TECHNOLOGY
BIT 3202 A/BBIT 304: DISTRIBUTED DATABASES/ADVANCED DATABASE SYSTEMS
FULL TIME/PART TIME/DISTANCE LEARNING
DATE: AUGUST, 2019 TIME: 2 HOURS
INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions.
QUESTION ONE
a) Explain the following forms of distributed tables 5Marks
i) Nonreplicated, nonfragmented (nonpartitioned)
ii) Fully replicated (all tables)
iii) Fragmented (also known as partitioned)
iv) Partially replicated (some tables or some fragments)
v) Mixed (any combination of the above)
b) Discuss the objectives of distribution design in databases 6 Marks
i) Fragmentation
ii) Replication
iii) allocation
c) Describe rules to be followed when fragmenting a database 6Marks
d) describe the process of query processing and optimization 4 Marks
e) Discuss three aspects of distribution transparency in DDBMS 9 Marks
QUESTION TWO
a) Discuss four basic types of semantic integrity constraints 8 Marks
b) What are the challenges faced in distributed semantic integrity control 4 Marks
c) Discuss properties of transactions that ensure the database remains correct and consistent
6Marks
d) Explain using an appropriate example the term transaction 2Marks
QUESTION THREE
a) Discuss the anomalies that are managed by the DDBMS scheduler in controlling concurrency
7Marks
b) Discuss the following locking principles in relational DBMSs
i) Lock Conversion 2 Marks
ii) Lock Upgrade 2 Marks
iii) Lock Escalation 2 Marks
iv) Multiple-Granularity Locking (MGL) 2 Marks
v) Intention Locking 2 Marks
c) In optimistic concurrency control, a transaction’s life cycle is divided into three phases, discuss
these phases 3Marks
QUESTION FOUR
a) Discuss the following objectives that must be considered in developing a distributed database
i) Locality of reference 2 Marks
ii) Improved availability and reliability of distributed data 2 Marks
iii) Workload distribution and improved performance 2 Marks
iv) Balanced storage capacities and costs 2 Marks
v) Minimal communication costs 2 Marks
b) A Distributed DBMS controls the storage and efficient retrieval of logically interrelated data that are
physically distributed among several sites. Discuss the components of a distributed DBMS.
10Marks
QUESTION FIVE
a) Discuss the two types of locks in databases 3 Marks
b) Discuss the following Two-Phase Locking in Distributed Systems 9 Marks
i) Centralized 2PL Centralized 2P
ii) Primary Copy 2PL
iii) Distributed 2PL
c) Explain the benefits provided by distributed databases 8 Marks
