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Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?
- a)Read locks are released immediately after a transaction reads a data item.
- b)Write locks are released immediately after a transaction writes a data item.
- c)Deadlocks can still occur even with strict 2PL.
- d)Multiple transactions can hold exclusive locks on the same data item simultaneously.
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
Which of the following is a correct statement about the strict two-pha...
While strict two-phase locking (2PL) protocol ensures serializability, it does not prevent deadlocks. Deadlocks can still occur when transactions hold exclusive locks and request additional locks that are being held by other transactions, resulting in a cyclic dependency. Additional techniques like deadlock detection and resolution are needed to handle deadlocks.
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Which of the following is a correct statement about the strict two-pha...
Explanation:
Strict two-phase locking (2PL) is a concurrency control protocol used in database management systems (DBMS) to ensure the serializability of transactions. It consists of two phases: the growing phase and the shrinking phase. In the growing phase, transactions acquire locks on the data items they access, and in the shrinking phase, transactions release the locks they acquired.
Deadlocks can still occur even with strict 2PL:
While strict 2PL provides a mechanism to prevent data inconsistencies and ensures serializability, it does not guarantee the prevention of deadlocks. Deadlocks occur when two or more transactions are waiting for each other to release the locks they hold. In strict 2PL, a transaction holds all its locks until it completes, and this can lead to potential deadlocks.
Example:
Consider two transactions T1 and T2, both of which need to acquire locks on two data items, A and B. If T1 acquires a lock on A and T2 acquires a lock on B, and both transactions then attempt to acquire the lock on the other data item, a deadlock occurs. T1 is waiting for T2 to release the lock on B, and T2 is waiting for T1 to release the lock on A. Neither transaction can proceed, resulting in a deadlock situation.
Solution:
To address deadlocks, additional techniques such as deadlock detection and deadlock prevention are employed. Deadlock detection involves periodically checking for the existence of deadlocks and resolving them if found. Deadlock prevention techniques aim to prevent the occurrence of deadlocks altogether.
In conclusion, while strict 2PL provides a mechanism for ensuring the serializability of transactions by acquiring and releasing locks, it does not guarantee the prevention of deadlocks. Deadlocks can still occur in strict 2PL, and additional techniques are required to detect and resolve or prevent deadlocks from happening.
Strict two-phase locking (2PL) is a concurrency control protocol used in database management systems (DBMS) to ensure the serializability of transactions. It consists of two phases: the growing phase and the shrinking phase. In the growing phase, transactions acquire locks on the data items they access, and in the shrinking phase, transactions release the locks they acquired.
Deadlocks can still occur even with strict 2PL:
While strict 2PL provides a mechanism to prevent data inconsistencies and ensures serializability, it does not guarantee the prevention of deadlocks. Deadlocks occur when two or more transactions are waiting for each other to release the locks they hold. In strict 2PL, a transaction holds all its locks until it completes, and this can lead to potential deadlocks.
Example:
Consider two transactions T1 and T2, both of which need to acquire locks on two data items, A and B. If T1 acquires a lock on A and T2 acquires a lock on B, and both transactions then attempt to acquire the lock on the other data item, a deadlock occurs. T1 is waiting for T2 to release the lock on B, and T2 is waiting for T1 to release the lock on A. Neither transaction can proceed, resulting in a deadlock situation.
Solution:
To address deadlocks, additional techniques such as deadlock detection and deadlock prevention are employed. Deadlock detection involves periodically checking for the existence of deadlocks and resolving them if found. Deadlock prevention techniques aim to prevent the occurrence of deadlocks altogether.
In conclusion, while strict 2PL provides a mechanism for ensuring the serializability of transactions by acquiring and releasing locks, it does not guarantee the prevention of deadlocks. Deadlocks can still occur in strict 2PL, and additional techniques are required to detect and resolve or prevent deadlocks from happening.
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Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer?
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Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer? for Software Development 2025 is part of Software Development preparation. The Question and answers have been prepared according to the Software Development exam syllabus. Information about Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Software Development 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer?.
Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer? for Software Development 2025 is part of Software Development preparation. The Question and answers have been prepared according to the Software Development exam syllabus. Information about Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Software Development 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Which of the following is a correct statement about the strict two-phase locking (2PL) protocol in DBMS?a)Read locks are released immediately after a transaction reads a data item.b)Write locks are released immediately after a transaction writes a data item.c)Deadlocks can still occur even with strict 2PL.d)Multiple transactions can hold exclusive locks on the same data item simultaneously.Correct answer is option 'C'. Can you explain this answer?.
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