1. Multidimensional Schemas in Data Warehousing

1.1 Star Schema

• Information in dimensions are de-normalized
• No subsets or Parent/Child dimensions

1.2 Snowflake Schema

• Some dimensions are normalized, resulting in subsets or Parent/Child dimensions
• eg: subcategory and category

1.3 Fast Constellation /Galaxy Schema

• Normalization in both the dimensions used and facts used for finding information
• Results in more dimensions and facts to be accessed

• two facts: they are normalized table , eg: factsales and factsalesdetails, you must know the detail information through the factsales

  
  example

1.4 hybrid

• combine those three schema

star
snowflake
fast constellation