In the SAP system, a business process is mapped by means of an SAP transaction, which can include several screen changes (for example, creating an order). The changes to the data caused by this business process should be written to the database in full or not at all. If the operation is canceled while the transaction is being executed, or if an error occurs, the transaction should not make any changes to the database. These activities are handled by the SAP update system, which is described below.
The update system also enhances reliability and performance, and makes it easier to restore the data when changes are made to the database.
Updates are closely related to the SAP lock concept, which is described in the documentation onThe SAP Lock Concept.
You can find further documentation on updates inUpdate Techniques in the ABAP documentation. This documentation explains how an application programmer can control the update logic using ABAP statements.
The update system is used to lighten the workload of the SAP transactions when time-consuming changes are made to the database. These are carried out asynchronously in special update 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.
Exactly how an update is made in the SAP system is described in the section entitledFunctional Description of Updates.
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