Transaction A transaction is a one or more operations on one or more databases that should be treated as a single unit of work. Applications specify when each transaction starts, what database operations are included in it, and when it ends.
Every transaction ends by committing or aborting .
If a transaction commits, Berkeley DB guarantees that any database changes included in the transaction will never be lost, even after system or application failure. If a transaction aborts, or is uncommitted when the system or application fails, then the changes involved will never appear in the database. System or application failure System or application failure is the phrase we use to describe something bad happening near your data. It can be an application dumping core, being interrupted by a signal, the disk filling up, or the entire system crashing. In any case, for whatever reason, the application can no longer make forward progress, and its databases are left in an unknown state.