Performance optimisation cleanup of Change logs and PSA
Scope of the Document: This document will provide a brief overview on the most preferred performance optimisation activities:
> Change log deletion
> PSA cleanup
Why do we have a cleanup activity?
The requests that are loaded in the PSA as well as the change log table of the DSO’s gets piled up in large numbers as days pass by. In any BW database, one third space is being occupied by the PSA/Change log; hence a proper strategy should be there for PSA/Change Log Deletion to delete the requests from the PSA and Change Log tables regularly by using the process types ‘Deleting Requests from the PSA’ and ‘Deleting Requests from the Change Log’ in all BI Systems in order to increase the desk space, costs of data retention, the downtime for maintenance tasks and the performance of the loading process.
In the advent of implementing the process chains for these performance , there can be challenges as the activity may possess some conditions/restrictions.Let us discuss the possible combination of selections for the clean up activities and the out comes.When both the selections in the right hand side were selected, the chain did not eliminate the un-updated requests. After analysis on the reasons behind them, it was identified that the selection pattern in the variant of the chain had been the reason.
As you see in the above screenshots,
The first tick mark clearly indicates that the process chain filters the successfully updated requests only.
The second tick mark which has the same sign as unupdated requests in the PSA says delete incorrect requests, not updated.
If we want to select the requests with a certain status then we can also do in the above screen. We can select the following status indicators in the above screen.
Let us try to understand the meaning of these phrases clearly.
Delete Successfully Updated Requests Only – This status will delete only requests which are successfully updated into corresponding Info Providers
Delete Incorrect Requests that were not updated – This status will delete only incorrect requests which are not successfully updated into the corresponding Info Providers.
Delete Successfully Updated Requests only -This status will delete only requests which are successfully updated into corresponding Data Store objects.
Delete Incorrect Requests that were not updated – This status will delete only incorrect requests which are not successfully updated into the corresponding Data Store Objects.
Delete Activation Requests only, No Load requests– This status will delete only the activation requests (requests that begin with ODSR_…). No load requests are deleted.
In these selection conditions there is no option to Delete Correct Requests that were not updated (correct requests that were not successfully updated into the corresponding Info Providers). Hence, in a scenario where all the types of requests(Successfully updated, Incorrect requests unupdated,Correct requests updated) has to be cleared off, then do not give any selections in the selection pattern variant. For other combinations, one can select the selection patterns accordingly.