06 April 2012

Data Warehouse - Star Schema vs Snowflake Schema

Star Schema
* All dimension tables can be joined directly to the fact table
* Easy for direct user access and often support simpler and more efficient queries
* Typically contains between three and eight dimension tables (can contain more as necessary)

Snowflake Schema
* One or more dimension tables do not join directly to the fact table; they join through other dimension tables
* Support ease of dimension maintenance due to normalization
* Normalization may save on storage space, but dimension tables don’t tend to be that large