Design Tip #142 Building Bridges

http://www.kimballgroup.com/2012/02/design-tip-142-building-bridges/

The dominant topologies of Data Warehouse modelling (Star, Snowflake) are designed with one-to-many relationships in mind. Query readability, performance, and structure degrades severely when faced with a many-to-many relationship in these modelling schemes.

   

1. Type2 Fact tables, how to let the BI report tools like BO, micro strategy support automatically extract correct date range data?

   

2.if one row in fact table has more than one row in the dimension tables, what should we do?

Normalize the fact table is a bad idea. It will cause your measures use more distinct for getting correct result.

Use a bridge table to join the fact table and dimension table.

   

3.add the bitmap index for the stage tables, if these tables we will take more batches. It will be more effective than B plus tree index in this case.

http://docs.oracle.com/cd/E11882_01/server.112/e25554/indexes.htm#DWHSG8131