(Snowflake Series): Dimensional Modelling
In modern analytics, efficiently organising and connecting business data is essential for meaningful insights. Dimensional Modelling schemas such as the star and snowflake schema are power data models that can be used to building high-speed analytical databases in platforms like snowflake.
In this article, we will look into:
what is dimensional modelling? What are the core components of dimensional models? What are the different schemas in dimensional modelling? When to use which schema?
What is Dimensional Modelling?
Dimensional modelling:
- is a design methodology specifically geared for data warehouses and business intelligence (BI) systems
- were the main goal is to organise data so it can be queried quickly and intuitively
- empowering both simple reporting and complex analytics.
Key Features of dimensional modelling
1. Simplifies data structures for end-users
2. Supports efficient aggregations and slicing/dicing of data
3. Optimised for read-heavy analytical workloads
What are the core components of dimensional models?
Dimensional models are designed around Fact & dimension tables.
Fact Table:
- Stores quantitative, measurable business data (e.g., sales amounts, revenue, units sold).
- Includes keys linking to dimension tables, and numerical metrics called “measures.”
Dimension Table
- Contains descriptive information, or context, for facts (e.g., product name, customer location).
- Typically textual, less frequently updated than fact tables.
What are the different schemas in dimensional modelling? And when to use which?
Star Schema:
- has a central fact table connected directly to multiple dimension tables.
- used when simplicity and speed are most important.
Snowflake Schema:
- is a normalised extension of the star schema. Dimension tables are further split into related sub-tables.
- used when data space savings and eliminating duplicated information are priorities.
Conclusion:
Dimensional modelling is a vital approach for structuring data in analytical environments, making it easier for users to derive insights from complex datasets. By focusing on fact and dimension tables, dimensional models facilitate efficient processing and querying of data, crucial for business intelligence tasks.
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