1
GATE CSE 2025 Set 2
MCQ (More than One Correct Answer)
+2
-0

Consider the database transactions T 1 and T 2, and data items X and Y . Which of the schedule(s) is/are conflict serializable?

GATE CSE 2025 Set 2 Database Management System - Transactions and Concurrency Question 1 English

A
$\mathrm{R} 1(\mathrm{X}), \mathrm{W} 2(\mathrm{X}), \mathrm{W} 1(\mathrm{Y}), \mathrm{W} 2(\mathrm{Y}), \mathrm{R} 1(\mathrm{X}), \mathrm{W} 1(\mathrm{X}), \operatorname{COMMIT}(\mathrm{T} 2), \operatorname{COMMIT}(\mathrm{T} 1)$
B
$\mathrm{W} 2(\mathrm{X}), \mathrm{R} 1(\mathrm{X}), \mathrm{W} 2(\mathrm{Y}), \mathrm{W} 1(\mathrm{Y}), \mathrm{R} 1(\mathrm{X}), \mathrm{COMMIT}(\mathrm{T} 2), \mathrm{W} 1(\mathrm{X}), \operatorname{COMMIT}(\mathrm{T} 1)$
C
$\mathrm{R} 1(\mathrm{X}), \mathrm{W} 1(\mathrm{Y}), \mathrm{W} 2(\mathrm{X}), \mathrm{W} 2(\mathrm{Y}), \mathrm{R} 1(\mathrm{X}), \mathrm{W} 1(\mathrm{X}), \mathrm{COMMIT}(\mathrm{T} 1), \operatorname{COMMIT}(\mathrm{T} 2)$
D
$\mathrm{W} 2(\mathrm{X}), \mathrm{R} 1(\mathrm{X}), \mathrm{W} 1(\mathrm{Y}), \mathrm{W} 2(\mathrm{Y}), \mathrm{R} 1(\mathrm{X}), \mathrm{COMMIT}(\mathrm{T} 2), \mathrm{W} 1(\mathrm{X}), \operatorname{COMMIT}(\mathrm{T} 1)$
2
GATE CSE 2024 Set 1
MCQ (More than One Correct Answer)
+2
-0

Consider the following read-write schedule $S$ over three transactions $T_{1}$, $T_{2}$, and $T_{3}$, where the subscripts in the schedule indicate transaction IDs:

$S: r_{1}(z); w_{1}(z); r_{2}(x); r_{3}(y); w_{3}(y); r_{2}(y); w_{2}(x); w_{2}(y);$

Which of the following transaction schedules is/are conflict equivalent to $S$?

A

$T_{1}T_{2}T_{3}$

B

$T_{1}T_{3}T_{2}$

C

$T_{3}T_{2}T_{1}$

D

$T_{3}T_{1}T_{2}$

3
GATE CSE 2022
MCQ (Single Correct Answer)
+2
-0.67

Let Ri(z) and Wi(z) denote read and write operations on a data element z by a transaction Ti, respectively. Consider the schedule S with four transactions.

S : R4(x), R2(x), R3(x), R1(y), W1(y), W2(x), W3(y), R4(y)

Which one of the following serial schedules is conflict equivalent to S?

A
T1 $$\to$$ T3 $$\to$$ T4 $$\to$$ T2
B
T1 $$\to$$ T4 $$\to$$ T3 $$\to$$ T2
C
T4 $$\to$$ T1 $$\to$$ T3 $$\to$$ T2
D
T3 $$\to$$ T1 $$\to$$ T4 $$\to$$ T2
4
GATE CSE 2021 Set 2
MCQ (Single Correct Answer)
+2
-0.66

Let S be the following schedule of operations of three transactions T1, T2 and T3 in a relational database system:

R2(Y), R1(X), R3(Z), R1(Y), W1(X), R2(Z), W2(Y), R3(X), W3(Z)

Consider the statements P and Q below:

P: S is conflict-serializable.

Q: If T3 commits before T1 finishes, then S is recoverable.

Which one of the following choices is correct?

A
P is true and Q is false.
B
Both P and Q are true.
C
P is false and Q is true.
D
Both P and Q are false.
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