Question

    Which of the following scenarios violates the Isolation property in the ACID properties of a transaction? 

    A A transaction reads data before the previous transaction commits, resulting in dirty reads. Correct Answer Incorrect Answer
    B A transaction rolls back after detecting a deadlock, ensuring consistency. Correct Answer Incorrect Answer
    C Multiple transactions write data concurrently but respect unique constraints. Correct Answer Incorrect Answer
    D A transaction is lost due to a server crash, but recovery is possible. Correct Answer Incorrect Answer
    E A transaction reads stale data after another transaction updates the same record. Correct Answer Incorrect Answer

    Solution

    The Isolation property ensures that the operations of a transaction are isolated from other transactions. In scenario A, when a transaction reads uncommitted data from another transaction (dirty reads), the Isolation property is violated. This leads to incorrect or inconsistent data being processed if the uncommitted transaction rolls back or is otherwise altered before completion. Ensuring isolation prevents such scenarios, as transactions should not be able to see the intermediate states of other transactions. Why Other Options are Incorrect: B) A transaction rolls back after detecting a deadlock: This preserves consistency and is not a violation of Isolation. C) Multiple transactions write data concurrently but respect unique constraints: This scenario adheres to isolation as each transaction operates in its own space without interference. D) A transaction is lost due to a server crash: This is related to the Durability property, not Isolation. E) A transaction reads stale data: This is a violation of Consistency or Atomicity, depending on the situation, but not necessarily Isolation.

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