BIT 3202A DISTRIBUTED DATABASES.

UNIVERSITY EXAMINATIONS: 2021/2022
EXAMINATION FOR BACHELOR OF SCIENCE IN SOFTWARE
DEVELOPMENT/BAC/BIT/BISF/BBIT
BIT 3202A: DISTRIBUTED DATABASES/BIT 304 ADVANCED DATABASE SYSTEMS
ORDINARY EXAMINATIONS
DATE: DECEMBER 2021 TIME: 2 HOURS
INSTRUCTIONS: Answer ALL QUESTIONS

QUESTION ONE
a) Using a diagram, describe the architecture of a typical database system. (5 Marks)
b) Describe the relational database model (3 Marks)
c) Describe the life cycle of data. (3 Marks)
d) Explain four applications of the database technology (4 Marks)
e) Using explain the concept of a distributed databases (5 Marks)
QUESTION TWO
a) Discuss the various techniques that are used to implement distributed databases concepts
shown in the diagram below [10 Marks]


b) Give an example of a set of requirements whose solution would need to combine.
Describe an architecture for integrating OLAP, OLTP and NoSQL in the distributed
databases system design. [5 Marks]
QUESTION THREE
a) Differentiate between a shared lock and an exclusive lock. (2 Marks)
b) Below are two transactions T3 and T4. Explain whether or not this will lead to a deadlock. Give a
reason for your answer. (4 Marks)


c) Imagine that it so happens that just when you are paying for a service using Mpesa, a friend is
sending you money via your Mpesa line. Explain how this concurrency is handled by the database
software in terms of the growing phase and the shrinking phase of transactions. (4 Marks)
d) Describe the steps of distributed query processing (5 Marks)
QUESTION FOUR
An Airline Reservation System enables the customer to do the things such as search for airline
flights for two travel cities on a specified date, choose a flight based on the details, reservation of
flight and cancellation of reservation.
The system allows the airline passenger to search for flights that are available between the two
travel cities, namely the “Departure city” and “Arrival city” for a particular departure and arrival
dates. The system displays all the flight’s details such as flight no, name, price and duration of
journey etc.
After search the system display list of available flights and allows customer to choose a particular
flight. Then the system checks for the availability of seats on the flight. If the seats are available,
then the system allows the passenger to book a seat. Otherwise it asks the user to choose another
flight.
To book a flight the system asks the customer to enter his details such as name, address, city, state,
credit card number and contact number. Then it checks the validity of card and book the flight and
update the airline database and user database. The system also allows the customer to cancel his/her
reservation, if any problem occurs. Discuss how a distributed database can be designed and
implemented for a web based airline reservation systems.
[15 Marks]

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