Classic and SAP BW Star Schema Comparisons

This post will summarize the comparisons (advantages anddisadvantages) between Classic Star Schema and SAP BW Star Schema. Note that there are so many similarities in the terminology and concepts used in SAP BW Star Schema compared with Classic Star Schema. The two critical terminologies different between them are dimension and attributes.

Here are terminology comparisons for the two:

Classic Star Schema	SAP BW Star Schema
Cube	InfoCube
Fact Table	Key Figure or KPI
Dimension Attribute	Characteristic, Attributes, Hierarchy Node
Dimension Table	Dimension Table, Master Data Table, External Table, SID Table
-	Standard Business Content
-	Hierarchies
-	MultiCube
-	Remote Cube

Advantages of Classic Star Schema

• Data access runs performantly due to the small number of joining operations.
• There are only join operations between the fact tables and the involved dimension tables.

Disadvantages of Classic Star Schema

• Redundant entries exist in the dimension tables
• Historization of dimensions is not easy to model. The dimension changing may be done slowly.
• No multi language capability
• It is difficult to model some hierarchy’s dimension.
• Query performance is also made worse, since aggregates and fact data are stored in the same table (fact table).

Advantages of the SAP BW Star Schema

• Faster access to data than via long alpha-numeric keys. SAP BW use automatically generated INT4 keys for SID and Dimension ID
• Can model in easy way: Historizing, multi-lingual, and shared dimensions. It is happen because of the excavation of master data from the dimension tables using the SID technique.
• The query performance is improved here as aggregated key figures can be stored in their own fact tables.

Those are the comparisons, advantages and disadvantages, between Classic and SAP BW Star Schema that I have noted untill now. No Wonder why SAP enhances the classic star schema and create they own data model, SAP BW Star Schema.