Multiple choice

In a particular schedule, transaction T2 reads a value previously written by transaction T1 and transaction T3 reads a value previously written by T2. Which of the following ensures the schedule to be cascade less schedule?

  1. T1 commits before T2 and T2 commits before T3.

  2. T1 commits after T2 and T2 commits before write operation of T3.

  3. T1 commits before T2 and T2 commits before write operation of T3.

  4. T1 commits at last and T2 and T3 can commit in any order.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a cascadeless schedule, transactions must commit before their dependent transactions read their data. Here T2 reads from T1, and T3 reads from T2. To ensure cascadelessness: T1 must commit before T2 reads, and T2 must commit before T3 reads. Option A correctly states this requirement.

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