Distributed Databases Question Paper
Distributed Databases
Course:Bachelor Of Science In Information Technology
Institution: Kca University question papers
Exam Year:2011
UNIVERSITY EXAMINATIONS: 2010/2011
THIRD YEAR EXAMINATION FOR THE DEGREE OF BACHELOR OF
SCIENCE IN INFORMATION TECHNOLOGY
BIT 4306: DISTRIBUTED DATABASES
DATE: APRIL 2011 TIME: 2 HOURS
INSTRUCTIONS: Answer question ONE and any other TWO questions
QUESTION ONE
a) Explain the following Four strategies regarding placement of data
i) Centralized (2 Marks)
ii) Partitioned (2 Marks)
iii) Complete Replication (2 Marks)
iv) Selective Replication (2 Marks)
b) In your own opinion which architecture is suitable for distributed databases (4 Marks)
c) Using examples elaborate on the importance of Database Links in distributed databases?
(4 Marks)
d) Using SQL show how Views can be used to create location transparency in a distributed
database (6 Marks)
e) Give reasons why a database is fragmented (8 Marks)
QUESTION TWO
a) The user has to perceive the DDB as a single, logical entity. Describe the four types of
distributed Transparency that facilitates a single system image (8 Marks)
b) Remote SQL Statements are in two categories; a remote query statement and a remote update
statement. Using examples differentiate between the two categories (4 Marks)
2
c) Using an example show how a remote update statements differs from Distributed SQL
Statements (4 Marks)
d) i) Define the term remote transaction (1 Mark)
ii) Describe using SQL how an object in a remote site can be accessed (3 Marks)
QUESTION THREE
a) Briefly explain how the Two-Phase Commit Mechanism in distributed databases ensures data
integrity (4 Marks)
b) Do you think the following are distributed database management systems or not?
i) Distributed Processing (2 Marks)
ii) Parallel DBMS (3 Marks)
c) Using a relevant example explain the concept of a Remote Procedure Calls (RPCs) in distributed
databases (6 Marks)
d) Briefly explain how Distributed Query Optimization is achieved in oracle databases
(5 Marks)
QUESTION FOUR
a) Explain the principle behind Distributed Catalogue Management (6 Marks)
b) Show how you can rewrite the following query using collocated inline views to improve
performance (6 Marks)
CREATE TABLE statement:
CREATE TABLE AS (
SELECT l.a, l.b, r1.c, r1.d, r1.e, r2.b, r2.c
FROM local l, remote1 r1, remote2 r2
WHERE l.c = r.c
AND r1.c = r2.c
AND r.e > 300
);
c) Using a well labeled diagram describe the reference architecture of a distributed database
management systems (8 Marks)
3
QUESTION FIVE
a) Outline any four applications that use distributed databases concepts (4 Marks)
b) What benefits are provided by views in databases? (6 Marks)
c) Query processing is a three step process that transforms a high-level query of relational calculus
into an equivalent and more efficient lower-level query of relational algebra. Describe the
activities involved in Query processing (6 Marks)
d) Elaborate on the properties of a transaction (4 Marks)
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