ACID properties of transactions Which ACID property guarantees that once a transaction commits, its changes are permanent and will survive failures?

Introduction / Context:
ACID—Atomicity, Consistency, Isolation, Durability—defines core guarantees for reliable transactions. Each property addresses a distinct concern, and durability handles permanence after commit.

Given Data / Assumptions:

• We are asked which property ensures permanence of committed changes.
• Standard transactional storage uses write-ahead logs, checkpoints, and crash recovery.

Concept / Approach:

Durability means that once the DBMS acknowledges COMMIT, the system guarantees the committed state will persist, even after crashes. Logging and recovery protocols ensure the database can be restored to the last committed state.

Step-by-Step Solution:

Verification / Alternative check:

Core database literature and vendor docs describe durability as guaranteed via WAL, fsync/flush semantics, and recovery mechanisms that reapply committed updates after a crash.

Why Other Options Are Wrong:

• Atomic: scope is commit vs. rollback, not persistence across crashes.
• Consistent: logical correctness, not physical permanence.
• Isolated: concurrency behavior, not storage survivability.
• Deterministic: not an ACID property.

Common Pitfalls:

• Equating durability with backup; backups are complementary, not the same guarantee.
• Assuming durability without proper hardware flushes or reliable storage.

Final Answer:

Durable.