Which property ensures that once committed, changes survive power loss?

Which property ensures that once committed, changes survive power loss?

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

Answer: (C)

Durability is the property that ensures once a transaction is committed, its effects are permanent even if the system crashes or loses power. This relies on writing the commit to nonvolatile storage and keeping a durable log so recovery procedures can restore the committed state after a failure. Atomicity focuses on all-or-nothing execution, but it doesn’t by itself guarantee persistence after a crash. Consistency ensures transitions respect the database rules, not the persistence of changes. Isolation controls visibility of concurrent transactions during execution, not durability. So the enduring nature of committed results after power loss is what durability guarantees.

Durability is the property that ensures once a transaction is committed, its effects are permanent even if the system crashes or loses power. This relies on writing the commit to nonvolatile storage and keeping a durable log so recovery procedures can restore the committed state after a failure. Atomicity focuses on all-or-nothing execution, but it doesn’t by itself guarantee persistence after a crash. Consistency ensures transitions respect the database rules, not the persistence of changes. Isolation controls visibility of concurrent transactions during execution, not durability. So the enduring nature of committed results after power loss is what durability guarantees.