it345,nawal

College of Computing and Informatics

Assignment 2
Deadline: Tuesday 15/4/2025 @ 23:59
[Total Mark for this Assignment is 8]
Student Details:
Name: ###

ID: ###

CRN: ###
Instructions:

• You must submit two separate copies (one Word file and one PDF file) using the Assignment Template on
Blackboard via the allocated folder. These files must not be in compressed format.

• It is your responsibility to check and make sure that you have uploaded both the correct files.
• Zero mark will be given if you try to bypass the SafeAssign (e.g. misspell words, remove spaces between
words, hide characters, use different character sets, convert text into image or languages other than English
or any kind of manipulation).

• Email submission will not be accepted.
• You are advised to make your work clear and well-presented. This includes filling your information on the cover
page.

• You must use this template, failing which will result in zero mark.
• You MUST show all your work, and text must not be converted into an image, unless specified otherwise by
the question.

• Late submission will result in ZERO mark.
• The work should be your own, copying from students or other resources will result in ZERO mark.
• Use Times New Roman font for all your answers.

Restricted – ‫مقيد‬

Question One

Pg. 01
Learning
Outcome(s): LO2
Apply the
concepts of
transaction
management,
concurrency, and
recovery of a
database.

Restricted – ‫مقيد‬

Question One

2 Marks

Given the system logs in the table below, which displays the sequence of operations of
transactions T1, T2, T3, and T4:
a) What is the role or purpose of implementing a checkpoint in this system?
b) In the event of a recovery using the deferred update method, which transactions
will be undone, which will be redone, and which will be ignored? In your
response, you should analyze the status of transactions T1, T2, T3, and T4,
providing an explanation for each based on the recovery process.
System logs
[start transaction, T1]
[write transaction, T1, D, 25]
[commit, T1]
[Checkpoint]
[start transaction, T2]
[write transaction, T2, C, 50]
[write transaction, T2, A, 10]
[commit, T2]
[start transaction, T3]
[write transaction, T3, B, 10]
[start transaction, T4]
[write transaction, T4, D, 35]
system crash

Question Two

Pg. 02
Learning
Outcome(s): LO2
Apply the
concepts of
transaction
management,

Question Two

2 Marks

The two transactions below lead to a deadlock. Demonstrate with examples how this
deadlock can be handled or prevented using the conservative and basic two-phase
locking protocols.
T’1

concurrency, and

read_lock (Y);

recovery of a

read_item (Y);

database.

T’2

read_lock (X);
read_item (X);
write_lock (X);
(waits for X)
write_lock (Y);
(waits for Y)

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Question Three

Pg. 03
Learning
Outcome(s): LO2
Apply the
concepts of

Question Three
Consider the following two transactions:
T1: read (X);
read (Y);

transaction
management,

B = X – Y;

concurrency, and

write (Y);

recovery of a
database.

T2: write (X);

.

read (Y);
•
•

Restricted – ‫مقيد‬

2 Marks

Add the necessary lock and unlock instructions to enforce the two-phase
locking protocol for both transactions.
Is it possible for a deadlock to occur? If so, provide an example of a schedule
where deadlock happens.

Question Four

Pg. 04
Learning
Outcome(s): LO2

Question Four

2 Marks

Apply the

Evaluate the following schedule of three transactions for serializability. Also,
determine if it’s possible to create an equivalent serial schedule. If so, explain how; if
not, provide reasons why it cannot be done.

concepts of

S1: r2(A); r1(B); w2(A); r2(B); r3(A); w1(B); w3(A); w2(B)

transaction
management,
concurrency, and
recovery of a
database.

Restricted – ‫مقيد‬

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