Designing Dimension Tables

What are Dimension Tables?

Dimension tables are structures that categorize facts and measures in order to enable users to answer business questions. They contain attributes that describe the facts, providing context to the data.

Characteristics of Dimension Tables

• Contain descriptive attributes (dimensions) used to filter, group, and label data.
• Typically have a primary key that uniquely identifies each record.
• Usually denormalized to optimize read performance.
• Often include hierarchies that allow for drill-down capabilities.

Designing Process

The design of a dimension table involves several important steps:

1. Define the purpose of the dimension.
2. Identify the attributes needed for the dimension.
3. Choose a primary key for the dimension.
4. Consider the relationships to other tables.
5. Optimize for query performance and user needs.

Here is a flowchart illustrating the designing process:

graph TD;
    A[Define Dimension Purpose] --> B[Identify Attributes];
    B --> C[Choose Primary Key];
    C --> D[Consider Relationships];
    D --> E[Optimize for Performance];
            

Best Practices

• Use meaningful names for dimensions and attributes.
• Limit the number of attributes to those that are necessary.
• Regularly review and update dimension tables to reflect changes in business needs.
• Document the design decisions and definitions for future reference.

FAQ