Which property ensures that a transaction is all-or-nothing?

• A. Consistency
• B. Atomicity
• C. Isolation
• D. Durability

Answer: (B)

Atomicity means a transaction is all-or-nothing. It’s treated as a single unit of work: either every operation in that unit completes and its effects are saved, or if any part fails, none of the changes take effect and the system rolls back to the state before the transaction began. This guarantees there are no partial updates, which is crucial for data integrity. For example, in transferring funds, both the debit and the credit must happen; if the credit cannot be completed, the debit is undone so no money is lost or misplaced. The other properties cover different aspects: consistency ensures data obeys rules, isolation prevents concurrent transactions from interfering with each other, and durability ensures once a transaction commits, its results persist despite crashes. So the all-or-nothing behavior is the hallmark of atomicity.