Design Tip #142 Building Bridges

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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.

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

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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.

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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

Design Tip #142 Building Bridges

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原文地址：http://www.cnblogs.com/huaxiaoyao/p/4242085.html