A database LUW is a non-separable sequence of database operations that ends in a database commit. The database LUW is either executed completely by the database system, or not at all. After a database LUW has been completed successfully, the database returns to a consistent status and a new database LUW is opened. If an error is discovered within a database LUW, all database changes made since the start of the database LUW can be canceled using a database rollback. The database is subsequently restored to the same status as before the start of the database LUW. Isolation levels are responsible for determining whether other users can perform reads on data modified in a database LUW, before a database commit is performed.
- At the end of a database LUW, all the reader streams and locators created in it are closed implicitly. A writer stream that is still open is only closed as part of a database rollback and causes a runtime error in a database commit.