In this unit, we will focus on recent changes in SAP BW/4HANA 2023, from SP 1 until SP 4. There are now settings in the DataStore object (advanced) maintenance editor for the optimization of the corresponding database table.
Delta merge is a database job that integrates recent data changes and existing, already compressed data of a table. The storage for the changes is called delta store, the storage with compressed data is called main store. Technically, this job is done by creating a new main store which finally replaces the old one. After the job, data read performance is improved.
In the BW Modeling tools, you can change the mode for execution of the delta merge in the technical settings for DataStore objects (advanced). This setting describes what triggers the delta merge job.
Auto Merge: This is the default setting for DataStore objects that have a write interface. Whenever changes are made to the data of a DataStore object as part of the write process, the system does not trigger a smart merge because a delta merge is executed for the activation in any case. This option is particularly useful in streaming and push scenarios and is therefore preset as the default setting for DataStore objects that have write interfaces.
Smart Merge: This is the default setting for all other DataStore objects, this means, DataStore objects that don't have a write interface. Whenever changes are made to the data of a DataStore object, the system triggers a smart merge.
Note
Before starting with SAP HANA Cloud, data lake Relational Engine as cold store, make sure you have applied the corrections provided with SAP Note 3570462.
Note that data records in the cold tier (external storage) cannot be changed, and no regular updates can be applied (due to write protection).