A cube is automatically converted to Columnstore (on the target system), if it is empty (on the target system).
Converting all Cubes to Columnstore
There are 3 different ways for converting all cubes to Columnstore. In the second tab of report MSSCSTORE, you can define a global setting for all SAP BW cubes. We aware, that this is a global setting for all (existing and future) cubes, not just a default for new cubes. When choosing "Always Column Store (CS)" and pressing F8, all cubes are defined in SAP BW as Columnstore Cubes. However, the Columnstore Indexes are not created on the database yet. Report MSSCSTORE should finish within a few minutes, since only the cube definition is changed.
Converting via process chain All indexes of a BW cube are created when running the BW process chain Type "Create Index" or executing "Repair DB indexes" in SAP transaction RSA1. This allows a gradual conversion of the cube indexes, once you have changed the Columnstore definition in report MSSCSTORE as described above.
Immediate conversion You might additionally select "Repair indexes of all cubes" in report MSSCSTORE. Hereby, the Columnstore Indexes are created on the database immediately. In this case, the runtime of report MSSCSTORE can easily take a few hours. Therefore, you should run report MSSCSTORE as a batch job (by pressing F9). Make sure that the SQL Server transaction log is large enough and that log backups are performed regularly.
Conversion during R3load System Copy You can automatically convert all cubes to Columnstore during an R3load-based system copy. Therefore, you have to choose "SQL Server 2016 (all column-store)" as the database version in report SMIGR_CREATE_DDL.
For SAP BW releases below 7.40 SP8 you should convert all BW cubes to Columnstore. For newer SAP BW releases you should consider applying the Flat Cube. A Flat Cube always uses the Columnstore.