Which ACID property ensures that a transaction brings the database from one…
2023
Which ACID property ensures that a transaction brings the database from one valid state to another, maintaining all predefined rules?
- A.
Atomicity
- B.
Consistency
- C.
Isolation
- D.
Durability
- E.
None of the above
Attempted by 49 students.
Show answer & explanation
Correct answer: B
Concept
The ACID properties guarantee reliable transaction processing in a database. Consistency is the property that requires every transaction to move the database from one valid state to another, so that all predefined rules — integrity constraints, keys, triggers, and business rules — continue to hold before and after the transaction. If a transaction would violate any such rule, it is not allowed to commit.
Application
The question asks which property keeps the database in a state that always satisfies every predefined rule. Preserving defined rules across a state change is exactly the definition of Consistency: the database is valid before the transaction and must remain valid after it, otherwise the transaction is rolled back.
Contrast with the other properties
Property | What it actually governs |
|---|---|
Atomicity | All-or-nothing execution: either every operation in the transaction happens or none does. Not about rule validity of the final state. |
Consistency | Moves the database from one valid state to another, enforcing all predefined rules — the property described here. |
Isolation | Concurrent transactions do not interfere; each behaves as if it ran alone. About concurrency, not rule validity. |
Durability | Once committed, changes survive crashes and power loss. About persistence, not maintaining valid states. |
"None of the above" is incorrect because Consistency is precisely the listed property that fits the description.
Therefore the property that brings the database from one valid state to another while maintaining all predefined rules is Consistency.