Power BI Data Modelling: Flat, Star, and Snowflake Schemas Explained

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Data modelling in Power BI involves connecting data sources, defining relationships, and structuring tables to turn raw records into an analytical model. The simplest approach is a flat schema, which stores all data in one wide table — easy to set up but prone to redundancy and poor performance at scale. A star schema improves on this by linking a central fact table to smaller dimension tables, boosting query performance and readability while reducing redundancy. The snowflake schema extends the star model further by normalising dimension tables into hierarchical sub-tables, improving storage efficiency and data integrity. Each schema offers distinct trade-offs between simplicity, performance, and scalability depending on dataset size and complexity.

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