COSC 3380 Exam 4 (From PPT)

After a transaction commits, the transaction can be rolled back.

a. Always

b. Sometimes

c. Never

c

Each example violates an ACID property. Match the property with the violation.

A transaction increases al employee salaries by 10%. Due to a system failure, increases for only half of the employees are written to the database.

a. Atomic

b. Consistent

c. Isolated

d. Durable

a

Each example violates an ACID property. Match the property with the violation.

A transaction withdraws $500 from account A and deposits $500 in account B. The withdrawal and deposit are written in the database, but due to a disk drive failure, the information is permanently lost.

a. Atomic

b. Consistent

c. Isolated

d. Durable

d

What was written?

105

What should be written?

105

What was written?

5

What should be written?

5

What was written?

92

What should be written?

92

Refer to the schedules in the above image. Use the initial values below for each question:

X	Y	Z
9	4	0

After Schedule executes, what is the value of Z?

3

Match the schedule type to the example schedule.

a. Serial schedule

b. Serializable schedule

c. Non-serializable schedule

a

A database ____ is a unit of work that is treated as a whole. It is either completed as a unit or failed as a unit.

a. commit

b. transaction

c. rollback

d. operation

b

In an online bank application that transfers funds from a checking account to a savings account, if a debit is made successfully from the checking account, the ____ property ensures that the corresponding credit is made to the savings account.

a. atomicity

b. consistency

c. isolation

d. durability 

a

In an online bank application that transfers funds from a checking account to a savings account, if a debit is made successfully from the checking account, the ____ property ensures that another transaction sees the transferred funds in one account or the other, but not in both, nor in neither.

a. atomicity

b. consistency

c. isolation

d. durability 

c

In an online bank application that transfers funds from a checking account to a savings account, if a debit is made successfully from the checking account, the ____ property ensures that the changes made to each account will not be lost due to a computer failure.

a. atomicity

b. consistency

c. isolation

d. durability 

b

A ___ is a sequential order of database instructions for multiple transactions.

a. Path

b. Schedule

c. Query

d. Transaction

b

Refer to the schedule below. The initial value of B is 7 and C is 3. What is the value of A after the schedule executes?

a. 2

b. 4

c. 7

d. 8

d

Theorem: A Schedule is Serializable iff it’s Serializable Graph is acyclic.

Is the following graph acyclic?

a. Yes

b. No

a

The following is a Serializable Graph corresponding to some Schedule.

Is the Schedule serializable?

a. Yes

b. No

a

Concurrent transactions in a serializable schedule are isolated.

a. True

b. False

a

The schedule above is serializable.

a. True

b. False

a

Is this schedule serializable?

Yes

Match the schedule type with the example schedule.

a. Serial schedule

b. Serializable schedule

c. Non-serializable schedule

a

Match the schedule type with the example schedule.

a. Serial schedule

b. Serializable schedule

c. Non-serializable schedule

b

Match the schedule type with the example schedule.

a. Serial schedule

b. Serializable schedule

c. Non-serializable schedule

c

The schedule is serializable.

a. True

b. False

No

The schedule is serializable.

a. True

b. False

b

Which one of the schedules are strict?

a. First one

b. Second one

c. Third one

d. Fourth one

d

Which two-phase locking technique results in the longest wait times for concurrent transactions?

a. Basic

b. Strict

c. Rigorous

Several transactions can hold concurrent shared locks on the same row.

a. True

b. False

a

Is there a cycle in this Wait-For Graph?

Yes

A database administrator is updating one of the tables in the database. Which of the following techniques can prevent other database administrators from doing concurrent transactions to the same table?

a. Mirroring

b. Scoping

c. Logging

d. Locking

d

A ____ is a part of the concurrency system that monitors, grants, and releases locks.

a. Lock Administrator

b. Lock System

c. Lock Manager

d. Lock Optimizer

c

In a ____, all transactions come to a halt and remain at a standstill until one of the transactions is aborted.

a. timeout

b. deadlock

c. two-phase locking

d. locking

b

Which deadlock management technique automatically rolls back a transaction when a lock is not released in a fixed period of time?

a. Timeout

b. Aggressive locking

c. Data ordering

d. Cycle detection

a

Refer to the table and schedule below. The UPDATE statement in transaction T1 holds an exclusive lock on the Class table. With strict two-phase locking, when does the SELECT statement in transaction T2 execute?

a. Immediately after the UPDATE statement in T1 executes

b. After the ROLLBACK statement in T1 executes

c. At the same time as the UPDATE statement in T1 executes

d. The SELECT statement in T2 will never execute

b