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Distributed Systems: Locking and Concurrency Control

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Distributed Systems: Locking and Concurrency Control

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Questions and Answers

What is the primary goal of timestamp-based concurrency control algorithms?

To increase the performance of concurrent transactions
To ensure that transactions commit in the order of their timestamps (correct)
To prevent deadlocks in a database system
To reduce the overhead of transaction management

What happens when two transactions, Ti and Tj, try to write the same data item simultaneously?

Both transactions rollback and restart
Tj's commit phase is delayed until Ti has committed (correct)
Ti's commit phase is delayed until Tj has committed
The younger transaction is aborted

What is the purpose of the access rule in timestamp-based ordering?

To ensure that older transactions commit before younger ones (correct)
To enforce two-phase locking protocol
To allow simultaneous access to data items
To prioritize younger transactions over older ones

What is the benefit of using timestamp-based concurrency control algorithms?

Ensured serializability and transaction isolation (C) Signup and view all the answers

What is the role of timestamps in concurrency control?

To prioritize transactions based on their start time (C) Signup and view all the answers

What is the effect of Rule 3 on transaction Ti and Tj?

Ti's commit phase cannot overlap with Tj's commit phase (A) Signup and view all the answers

What is the consequence of violating the access rule in timestamp-based ordering?

The equivalent serial schedule is disrupted (B) Signup and view all the answers

What is the primary difference between optimistic and pessimistic concurrency control?

Optimistic control assumes conflicts are rare, while pessimistic control assumes conflicts are common (D) Signup and view all the answers

Which of the following is NOT a type of timestamp-based concurrency control algorithm?

Two-Phase Locking Protocol (C) Signup and view all the answers

What is the primary advantage of using timestamp-based concurrency control algorithms?

Ensured serializability and transaction isolation (A) Signup and view all the answers