Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery.
Which of the following statements is/are correct?
A
The same undo and redo list will be used while recovering again.
B
The database will become inconsistent.
C
All the transactions that are already undone and redone will not be recovered again.
D
The system cannot recover any further.
2
GATE CSE 2021 Set 1
MCQ (Single Correct Answer)
+2
-0.67
Let ri(z) and wi(z) denote read and write operations respectively on a data item z by a transaction Ti. Consider the following two schedules.
S1 : r1(x) r1(y) r2(x) r2(y) w2(y) w1(x)
S2 : r1(x) r2(x) r2(y) w2(y) r1(y) w1(x)
Which one of the following options is correct?
A
S1 is conflict serializable, and S2 is not conflict serializable.
B
S1 is not conflict serializable, and S2 is conflict serializable.
C
Both S1 and S2 are conflict serializable.
D
Neither S1 nor S2 is conflict serializable.
3
GATE CSE 2020
MCQ (Single Correct Answer)
+2
-0.67
Consider a schedule of transactions T1 and T2 :
Here, RX stands for “Read(X)” and WX stands for “Write(X)”. Which one of the following schedules is conflict equivalent to the above schedule?
A
B
C
D
4
GATE CSE 2016 Set 2
MCQ (Single Correct Answer)
+2
-0.6
Consider the following database schedule with two transactions, T1 and T2
S = r2(X); r1(X); r2(Y); w1(X); r1(Y); w2(X); a1; a2
where ri(Z) denotes a read operation by transaction Ti on a variable Z, wi(Z) denotes a write operation by Ti on a variable Z and ai denotes an abort by transaction Ti
.
Which one of the following statements about the above schedule is TRUE?
