In a star schema, what is the relationship between the central table and the dimension tables?

• A. The central fact table connects to denormalized dimension tables.
• B. Dimension tables are normalized into multiple related tables.
• C. There is no central fact table; all tables are independent.
• D. The schema uses only a single flat table.

Answer: (A)

In a star schema, the central fact table stores the measurable facts and includes foreign keys that point to each dimension. The surrounding dimension tables describe those dimensions with their attributes and are denormalized, meaning they’re kept in single, flat tables rather than split into multiple related ones. The fact table connects directly to each denormalized dimension table, forming the characteristic star shape. This arrangement allows straightforward, fast aggregations by joining the central fact table to the dimension tables without navigating through normalized structures.

Normalized dimension tables (split into multiple related tables) describe a different schema style (snowflake), and there is indeed a central fact table in a star schema. A single flat table would eliminate the dimensional separation that the star structure relies on.