The DB Transaction Start and DB Transaction End nodes allow you to model a database transaction, i.e. a unit of work that is either completely processed or not at all. So, if all nodes between the DB Transaction Start and DB Transaction End nodes execute successfully, all changes will be persisted in the database. Likewise, if any of the nodes between the two transaction nodes fails, none of the changes will be persisted in the database. Note that most databases do an implicit commit when executing a DDL statement such as create or drop table even within a transaction.