Star Schema Vs Snowflake Schema Vs Fact constellation Schema
Data Warehousing Schemas
- Star Schema
- Snowflake Schema
- Fact Constellation
- A single large central fact table and one table for each dimension
- Every fact points to one tuple in each of the dimensions and has additional attributes
- Does not capture hierarchies directly.
- Variant of star schema model.
- A single, large and central fact table and one or more tables for each dimension.
- Dimension tables are normalized split dimension table data into additional tables.
- Multiple fact tables share dimension tables.
- This schema is viewed as collection of stars hence called galaxy schema or fact constellation.
- Sophisticated application requires such schema.
- Afco Foods & Beverages is a new company which produces dairy, bread and meat products with production unit located at Baroda.
- There products are sold in North, North West and Western region of India.
- They have sales units at Mumbai, Pune , Ahmadabad ,Delhi and Baroda.
- The President of the company wants sales information.
- Report: The Number of units sold.
- Report : The Number of units sold over Time.
Building Data Warehouse
- Data Preprocessing
- Fill missing values
- Remove inconsistency
- Data Transformation & Integration
- Data Loading
Data in warehouse is stored in form of fact tables and dimension tables.
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