Saturday, March 24, 2012

Snow flake schema


Snowflake schema

The snowflake schema is an extension of the star schema, where each point of the star explodes into more points. In a star schema, each dimension is represented by a single dimensional table, whereas in a snowflake schema, that dimensional table is normalized into multiple lookup tables, each representing a level in the dimensional hierarchy.



Advantages:
  1. The biggest advantage of snowflake schema is improved query performance.
  2. Reduces dimension table size.

Disadvantage:
  1. Additional maintenance efforts needed due to the increase number of lookup or detail tables

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