Designing Star Schemas

Introduction

A star schema is a type of database schema that is used to organize data into a format that is optimal for data warehousing and analytical querying. It consists of a central fact table surrounded by dimension tables.

Key Concepts

• **Fact Table**: Contains quantitative data for analysis.
• **Dimension Table**: Contains descriptive attributes related to the fact data.
• **Primary Key**: Unique identifier for each record in a dimension table.
• **Foreign Key**: References the primary key from the dimension table in the fact table.

Step-by-Step Process

1. Identify the business process to model.
2. Determine the grain of the fact table (e.g., daily sales).
3. Identify the dimensions related to the fact (e.g., Time, Product, Customer).
4. Define the attributes for each dimension.
5. Design the schema diagram with the fact table at the center and dimensions surrounding it.

flowchart TD
    A[Identify Business Process] --> B[Determine Grain]
    B --> C[Identify Dimensions]
    C --> D[Define Attributes]
    D --> E[Design Schema Diagram]
            

Best Practices

• Keep dimension tables denormalized for performance.
• Limit the number of foreign keys in the fact table.
• Ensure appropriate indexing on fact and dimension tables.
• Regularly review and optimize schema based on usage patterns.