Rollback

What Does Rollback Mean?

A rollback is the operation of restoring a database to a previous state by canceling a specific transaction or transaction set. Rollbacks are either performed automatically by database systems or manually by users.

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Techopedia Explains Rollback

When a database user changes a data field but has not yet saved the change, the data is stored in a temporary state or transaction log. Users querying the unsaved data see the unchanged values. The action of saving the data is a commit; this allows subsequent queries for this data to show the new values.

However, a user may decide not to save the data. Under this condition, a rollback command manipulates the data to discard any changes made by the user, and does so without communicating this to the user. Thus, a rollback occurs when a user begins changing data, realizes the wrong record is being updated and then cancels the operation to undo any pending changes.

Rollbacks also may be issued automatically after a server or database crash, e.g. after a sudden power loss. When the database restarts, all logged transactions are reviewed; then all pending transactions are rolled back, allowing users to reenter and save appropriate changes.

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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.