For performance reasons, data that is not changed very often in the database is held in internal buffers in the SAP System. This data is accessed in these buffers instead of it being read from the database each time. If buffered data is changed, the relevant buffer contents must be invalidated.
The procedure used for this is called buffer synchronization.
Two software components are involved in controlling this synchronization:
Each of these components has parameters controlling their behavior:
In the transport profile, the parameterbuffreset can have the values 1 or 0. If the parameter is not specified explicitly in this file, tp takes the default value 1.
Synchronization is controlled in the SAP System with the profile parameterrdisp/bufrefmode . This parameter controls whether:
Values recommended forbufrefmode are:
bufrefmode = sendoff,exeauto
bufrefmode = sendon,exeauto
Also note the SAP profile parameterrdisp/bufreftime .
It regulates the intervals at which the application server is checked to see if buffered data has been invalidated. Only when each application server has read the entry for the invalidation of the data is the changed date the same throughout the SAP Systems.
When changed ABAP Dictionary objects are imported, transactions may terminate. The same can occur when the respective changes are made in the SAP System. The transport programstp / R3trans should be regarded as an additional application server.
As a result of structural changes, an instance may regenerate an ABAP program due to nametab changes before being able to synchronize its own nametab buffer. At runtime (now with a current nametab), the table work area no longer matches the structure used at generation time. The program terminates withGETWA_CANT_CLEAR .
Postpone imports of transports with changed ABAP Dictionary objects to a time when there is not much system activity, for example at night.