What happens in preemption when two transactions are initiated from the same base period?

In preemption scenarios involving transactions initiated from the same base period, it is important to understand how system resources are managed. The correct answer highlights that the job that completes first is accepted, while the other job must undergo modification to resolve conflicts that arise due to the simultaneous transactions.

This concept of preemption is critical in transaction management since it relates to ensuring data integrity and consistency. When two transactions from the same base period are executed, they typically have overlapping data dependencies. Thus, the system needs to enforce a rule where only one transaction can be fully accepted at a time, especially one that has completed its operation or yielded a result.

Once the first transaction finishes, it can be committed, and its results will be used. The second transaction, in contrast, is likely to require modification because it may be trying to access or modify the same data or resources that the first transaction has already changed or committed. Therefore, modifications might involve re-evaluating the second transaction’s parameters or its execution order to maintain the integrity of the system and ensure that no incorrect or outdated data is processed.

This mechanism protects the system from potential incorrect states, ensuring that data consistency and isolation are preserved while allowing efficient transaction processing. In contrast, the other choices present scenarios that either