A snowflake schema is a model for data configuration in a data warehouse or data mart in which a fact table is linked to multiple dimension tables that in turn are linked to other, related dimension tables, extending outward from the fact table at the center, much like the structure of a snowflake.
Snowflake schemata are similar to star schemata—in fact, the core of a snowflake schema is essentially a star schema. However, unlike a star schema, a dimension table in a snowflake schema is divided out into more than one table, and placed in relation to the center of the snowflake by cardinality. Breaking up dimension tables in this way provides many advantages in querying, as it eliminates redundancies, is more flexible and can take up less space.
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