ADB Final Exam Questions and Answers Fully Solved
During simultaneous execution each operation should be interleaved with the others, ensuring no
interference with the other operations. This maintains a database's... - Answers Concurrency
The system has entered an undesirable state (eg, deadlock) as a result of which a transaction cannot
continue with its normal execution. This is called - Answers Logical Error
Which isolation level has the highest risk of blocking? - Answers Serializable
Consider the following transaction involving two bank accounts x and y.
read (x); x := x-50 ; write (x); read (y); y:= y + 50; write (y)
The constraint that the sum of the accounts x and y should remain constant is that of
T1: read(x)
x := x -50
write(x)
T2: read(y)
y := y+50
write(y)
Before transaction: initially
x=100 and y =150 then x + y = 250
After transaction: finally
x=50 and y=200 then x + y =250
The constraint that the sum of the accounts x and y should remain constant is that of ... - Answers
Atomicity
Phantom reads occur when a transaction rereads data it has previously read and finds new rows that
were inserted by a different transaction. True or False - Answers True
In what case would a database prefer the 2PL protocol? - Answers When the system needs to avoid the
problem of lost updates.
During simultaneous execution each operation should be interleaved with the others, ensuring no
interference with the other operations. This maintains a database's... - Answers Concurrency
The system has entered an undesirable state (eg, deadlock) as a result of which a transaction cannot
continue with its normal execution. This is called - Answers Logical Error
Which isolation level has the highest risk of blocking? - Answers Serializable
Consider the following transaction involving two bank accounts x and y.
read (x); x := x-50 ; write (x); read (y); y:= y + 50; write (y)
The constraint that the sum of the accounts x and y should remain constant is that of
T1: read(x)
x := x -50
write(x)
T2: read(y)
y := y+50
write(y)
Before transaction: initially
x=100 and y =150 then x + y = 250
After transaction: finally
x=50 and y=200 then x + y =250
The constraint that the sum of the accounts x and y should remain constant is that of ... - Answers
Atomicity
Phantom reads occur when a transaction rereads data it has previously read and finds new rows that
were inserted by a different transaction. True or False - Answers True
In what case would a database prefer the 2PL protocol? - Answers When the system needs to avoid the
problem of lost updates.
