Virtual Labs

2 Phase Commit with and without failures

What is the primary goal of a commit protocol in distributed systems?

a: To improve performance of distributed transactions Explanation

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b: To ensure that all participants either commit or abort a transaction Explanation

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c: To reduce network communication between nodes Explanation

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d: To minimize the number of database locks required Explanation

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In distributed transactions, what property is most challenging to maintain across multiple nodes?

a: Consistency Explanation

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b: Isolation Explanation

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c: Atomicity Explanation

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d: Durability Explanation

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What is the main problem with a one-phase commit protocol?

a: It requires too many network messages Explanation

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b: It cannot handle concurrent transactions Explanation

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c: If the coordinator fails mid-execution, atomicity can be violated Explanation

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d: It is too slow for practical applications Explanation

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What happens when a participant receives a PREPARE message in the two-phase commit protocol?

a: It immediately commits the transaction Explanation

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b: It logs its readiness state and votes on whether it can commit Explanation

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c: It sends an acknowledgment to all other participants Explanation

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d: It releases all locks and resources Explanation

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In two-phase commit, what determines whether the coordinator decides to commit or abort?

a: The coordinator's own assessment of the transaction Explanation

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b: A majority vote from the participants Explanation

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c: Whether ALL participants vote to commit Explanation

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d: The participant with the highest priority Explanation

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What is the purpose of durable logging in the two-phase commit protocol?

a: To improve transaction performance Explanation

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b: To enable recovery after node failures Explanation

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c: To maintain transaction statistics Explanation

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d: To support transaction rollback Explanation

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What is the blocking problem in two-phase commit?

a: Participants cannot process other transactions while waiting Explanation

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b: The coordinator becomes a bottleneck for all transactions Explanation

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c: Participants in READY state cannot unilaterally decide to abort if coordinator fails Explanation

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d: Network congestion prevents messages from being delivered Explanation

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In the presumed abort optimization, what happens when a participant cannot find a transaction record after recovery?

a: It assumes the transaction committed Explanation

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b: It contacts other participants for the decision Explanation

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c: It assumes the transaction was aborted Explanation

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d: It waits indefinitely for coordinator contact Explanation

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What is a key trade-off when choosing timeout values in two-phase commit?

a: Memory usage versus processing speed Explanation

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b: Security versus accessibility Explanation

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c: Sensitivity to failures versus false timeouts under high latency Explanation

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d: Consistency versus availability Explanation

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