Distributed unit of work
Distributed unit of work (DUW) enables a user or application program to read or update data at multiple locations within a unit of work.
Within one unit of work, an application running on one system can direct SQL requests to multiple remote database management systems using the SQL supported by those systems. For example, the shop inventory program can perform updates to the inventory table on one system and the accounts receivable table on another system within one unit of work. The following figure illustrates this idea. Figure 1. Distributed unit of work in a distributed relational database
The target of the requests is controlled by the user or application with SQL statements such as CONNECT TO and SET CONNECTION. Each SQL statement must refer to data at a single location.
When the application is ready to commit the work, it initiates the commit; commitment coordination is performed by a synchronization-point manager or a transaction manager.
DUW allows update access or read-only access to multiple database management systems in one unit of work.
Whether an application can update a given database management system in a unit of work is dependent on the level of DRDA® (if DRDA is used to access the remote relational database) and the order in which the connections and updates are made.