Durability (computer science)

For example, if a flight booking database system reports that a seat has successfully been booked, then the seat will remain booked even if the system crashes. Durability also a guarantees that the system won't rollback the transaction because the seat was double-booked. (The system must check this before it acknowledges the seat has been booked)

The only way a transaction can be undone after it has been committed is by a compensatory transaction[?].

Durability is usually implemented by flushing the transaction's log records to disk before acknowledging commitment. In distributed transactions[?], all participating servers must acknowledge that they have stored all data and checked all consistency constraints before commit can be acknowledged. This is usually done by a two-phase commit[?] protocol.