Updates in the SAP System (BC-CST-UP) 
In the SAP system (Application Server ABAP), a business process is mapped by means of an SAP transaction, which can include several screen changes (for example, creating an order). The data changes caused by this process should be completely executed in the database, or not at all. If the procedure fails during the transaction, or an error occurs, the transaction should not cause any database changes. These activities are handled by the SAP update system, which is described below.
The update system offers increased security, performance, and the ability to recover when making database changes.
Features
The update system is used to lighten the workload of the SAP transactions when time-consuming changes are made to the database. These are then carried out asynchronously in special updating work processes. The update system also avoids rollback problems that occur as a result of the differences between the logical units of work (LUW) in an SAP transaction and in the database.
The documentation is split up into the following sections:
Features of the Update describes update concepts, architecture, and functions.
SAP Update: Configuration and Administration describes the configuration and administration tasks for the update system.
Analyzing and Correcting Update Errors provides information about solving problems.