Change Log Deletion in BW On HANA
SAP HANA memory is very expensive; it’s wise to clean out unnecessary memory when running your SAP BW system on SAP HANA. Of course PSA’s are regularly cleaned (this was usually already initiated when running you SAP BW system on a non-SAP HANA database) as no reporting is done on PSA data. Other ‘tables’ which consume a huge amount of data and which are not used for reporting are your so called change logs (delta tables).
These should be deleted on a regular basis to free up your much required SAP HANA memory.
To easily clean up change log data, the “Deletion of requests from the change log” process chain functionality can be used:
Based on which ‘level’ of your LSA++ architecture your DSO is residing, you can, for example, add several change log deletion steps. (Eg. Data Aquisition layer DSO’s can have a data retention of 30 days while Architected Data Marts have a data retention of 15 days)
The “Deletion of requests from the change log” process comes with 3 different flavours, as to be seen in the picture below:
1. Only successfully booked requests; Set this indicator if you only want to delete requests that have the quality status OK and were updated successfully.
2. Only requests with errors, not updated in any data target; Set this indicator if you only want to delete requests that contain errors and that were not yet updated or no longer exist in any data target.
3. Delete Activation Requests Only; No Load Requests; Only activation requests (requests that begin with ODSR_… ) are deleted. No load requests are deleted.
When running SAP BW 7.4 on SAP HANA, option 3 is required to actually have the process chain deleting change log data