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Commonly confused · Data & Analytics

Star Schema vs Snowflake Schema: What's the Difference?

Both are dimensional models with a central fact table surrounded by dimensions. In a star schema the dimension tables are denormalized and join directly to the fact table. In a snowflake schema the dimensions are normalized into multiple related sub-tables, reducing redundancy but adding joins.

Star Schema

Full definition
vs

Snowflake Schema

Full definition
Star SchemaSnowflake Schema
Dimension tablesDenormalized, one table per dimensionNormalized into multiple tables
Joins neededFewerMore
Query performanceGenerally faster and simplerCan be slower
Storage redundancyHigherLower
Ease of use for BIEasierHarder
ExampleProduct dimension includes category nameProduct links to a separate Category table
Remember it

A star keeps each point simple; a snowflake branches each point out.

Exam tip

BI exams, including Power BI, favor the star schema for performance and simplicity. Know the difference between fact tables (measures, foreign keys) and dimension tables (descriptive attributes).

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