Learn in the textbookFailure Recovery
DefinitionA rollback (ロールバック) is the operation that cancels the updates of a transaction that did not finish normally and restores the data to what it was before that processing began.
ExplanationThe undo uses the before-update values saved in the log to put each rewritten item back to its original value. It is carried out not only after failures but also when a transaction stops midway because of a program error or a user cancellation. As a result, a half-finished set of updates is never left in the database.
AnalogyIt is like making a mistake halfway through filling in an application form, throwing that sheet away, and starting again from a blank one.
Memory hookRoll back means to rewind. Back points backward, which ties it to backward restoration.