In a COMMIT, all the changes made by a transaction or a subtransaction on the database instance are recorded.
· Changes closed with a COMMIT can no longer be reversed with a ROLLBACK.
· As a result of a COMMIT, a new transaction is implicitly opened.
In normal database operation, the database system performs the required COMMIT actions independently. However, COMMIT can also be explicitly requested using appropriate SQL statements.
In a restart, the system checks which transactions were closed with a COMMIT. These actions are redone. Transactions not yet closed with a COMMIT are undone.