In a CompositeProvider, you can merge data from BW InfoProviders with data from SAP HANA views using union and join, or just merge data from BW InfoProviders and SAP HANA views.
The CompositeProvider's join and union operations are performed in SAP HANA. You can run queries on CompositeProviders just like on all other BW InfoProviders. You acquire SQL access to the data if you generate a SAP HANA view from the CompositeProvider.
Delta extraction by DTP is supported for CompositeProviders with unions based on DataStore objects (advanced) that have the properties Activate/Compress Data and All Characteristics are Key, Reporting on Union of Inbound and Active Table and thus behave like an InfoCube.
Delta extraction by DTP is also supported for CompositeProviders with union, which are based on InfoCubes.