Compensating transaction

When processing data it is useful to split the processing into transactions, where each transaction may consist of several individual operations yet, as a whole, moves the system between consistent states. In the context of a database this is often easily achieved using transactions and the commit/rollback mechanism.

For systems without a commit/rollback mechanism available, one can undo a failed transaction with a Compensating Transaction, which will bring the system back to its initial state. Typically, this is only a workaround which has to be implemented manually and cannot guarantee that the system always ends in a consistent state. The system designer may need to consider what happens if the compensating transaction also fails.

Compensating Transactions are also used in case where a transaction is long lived (commonly called Saga Transactions), for instance in a business process requiring user input. In such cases data will be commited to permanent storage, but may subsequently need to be rolled back.