Computer Science Engineering (CSE) Exam > Computer Science Engineering (CSE) Questions > For the schedule given below, which of the fo...
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For the schedule given below, which of the following is correct?
1 Read A
2 Read B
3 Write A
4 Read A
5 Write A
6 Write B
7 Read B
8 Write B
1 Read A
2 Read B
3 Write A
4 Read A
5 Write A
6 Write B
7 Read B
8 Write B
- a)This schedule is serializable and can occur in a scheme using 2PL protocol.
- b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.
- c)This schedule is not serializable but can occur in a scheme using 2PL protocol.
- d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.
Correct answer is option 'D'. Can you explain this answer?
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Verified Answer
For the schedule given below, which of the following is correct?1 Read...
Initial read of A is done by T1, whereas final write of B is also done by T1. Therefore W1(A), R2(A) and W2(B), R1 (B) are conflicting pairs. The schedule is neither T1 → T2 nor T2 →T1 serializable. Since schedule is not serializable, it can’t occur in a scheme using 2PL protocol.
Most Upvoted Answer
For the schedule given below, which of the following is correct?1 Read...
Schedule Analysis:
The given schedule consists of a series of read and write operations on two variables A and B. Let's analyze the schedule to determine its serializability and whether it can occur in a scheme using the Two-Phase Locking (2PL) protocol.
Conflict Serializability:
To determine whether a schedule is serializable, we need to check for conflicts between operations. In this case, conflicts occur when two operations access the same variable and at least one of them is a write operation.
Conflict Analysis:
1. Read A: No conflicts.
2. Read B: No conflicts.
3. Write A: No conflicts.
4. Read A: Conflict with operation 1 (Read A).
5. Write A: Conflict with operation 1 (Read A).
6. Write B: No conflicts.
7. Read B: Conflict with operation 2 (Read B).
8. Write B: Conflict with operation 6 (Write B).
Serializability:
Since the schedule has conflicts, it is not serializable. To be serializable, a schedule must be conflict-serializable, meaning that the order of conflicting operations can be rearranged without changing the final result.
Two-Phase Locking (2PL):
The 2PL protocol ensures serializability by acquiring and releasing locks on resources in two phases: the growing phase and the shrinking phase.
- In the growing phase, a transaction acquires locks on resources before accessing them.
- In the shrinking phase, a transaction releases locks on resources after completing its operations.
2PL Analysis:
In the given schedule, the conflicts between operations 4 and 5 (Read A and Write A) cannot be resolved using the 2PL protocol. According to 2PL, a write operation needs to acquire an exclusive lock (X-lock) on a resource, and a read operation needs to acquire a shared lock (S-lock) on a resource. Since operation 4 (Read A) conflicts with operation 5 (Write A), it violates the 2PL protocol.
Conclusion:
Based on the conflict analysis and 2PL protocol, we can conclude that the given schedule is not serializable and cannot occur in a scheme using the 2PL protocol. Therefore, the correct answer is option 'D'.
The given schedule consists of a series of read and write operations on two variables A and B. Let's analyze the schedule to determine its serializability and whether it can occur in a scheme using the Two-Phase Locking (2PL) protocol.
Conflict Serializability:
To determine whether a schedule is serializable, we need to check for conflicts between operations. In this case, conflicts occur when two operations access the same variable and at least one of them is a write operation.
Conflict Analysis:
1. Read A: No conflicts.
2. Read B: No conflicts.
3. Write A: No conflicts.
4. Read A: Conflict with operation 1 (Read A).
5. Write A: Conflict with operation 1 (Read A).
6. Write B: No conflicts.
7. Read B: Conflict with operation 2 (Read B).
8. Write B: Conflict with operation 6 (Write B).
Serializability:
Since the schedule has conflicts, it is not serializable. To be serializable, a schedule must be conflict-serializable, meaning that the order of conflicting operations can be rearranged without changing the final result.
Two-Phase Locking (2PL):
The 2PL protocol ensures serializability by acquiring and releasing locks on resources in two phases: the growing phase and the shrinking phase.
- In the growing phase, a transaction acquires locks on resources before accessing them.
- In the shrinking phase, a transaction releases locks on resources after completing its operations.
2PL Analysis:
In the given schedule, the conflicts between operations 4 and 5 (Read A and Write A) cannot be resolved using the 2PL protocol. According to 2PL, a write operation needs to acquire an exclusive lock (X-lock) on a resource, and a read operation needs to acquire a shared lock (S-lock) on a resource. Since operation 4 (Read A) conflicts with operation 5 (Write A), it violates the 2PL protocol.
Conclusion:
Based on the conflict analysis and 2PL protocol, we can conclude that the given schedule is not serializable and cannot occur in a scheme using the 2PL protocol. Therefore, the correct answer is option 'D'.
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For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer?
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For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer?.
For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for For the schedule given below, which of the following is correct?1 Read A2 Read B3 Write A4 Read A5 Write A6 Write B7 Read B8 Write Ba)This schedule is serializable and can occur in a scheme using 2PL protocol.b)This schedule is serializable but cannot occur in a scheme using 2PL protocol.c)This schedule is not serializable but can occur in a scheme using 2PL protocol.d)This schedule is not serializable and cannot occur in a scheme using 2PL protocol.Correct answer is option 'D'. Can you explain this answer?.
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