Until recently, Business Warehouse(BW) was relatively unique among data warehousing platforms in that it is, by default, fully model-driven. This means that a BW developer uses BW's interface to specify the data flow and storage of a data warehousing scenario, and then BW handles instantiating the model on the database and running the processes to ingest, transform and store data. This model has become more common in the cloud era.
For BW specifically, being model-driven meant developers would log in to the SAP GUI and use transaction codes like RSA1 to build their data warehousing scenarios, rather than using SQL and stored procedures in a database management system. More recently, BW development activities have moved to open source Eclipse and web-based tooling based on the SAP Fiori design language. The models defined in these tools are deployed on a development system, tested and migrated to quality assurance and production systems.
Up until BW on HANA, BW always ran on the SAP NetWeaver ABAP platform but was database-agnostic, supporting all databases that NetWeaver supported, including Oracle, Microsoft SQL Server and IBM DB2. Beginning with BW on HANA and continuing through BW/4HANA, BW still runs on the NetWeaver ABAP platform but requires the use of the HANA database. Many customers still use BW 7.5, the last database-agnostic release, on non-HANA databases.
