Question 7 In a Snowflake schema Select an option: (A) The fact tables are normalized and stored as multiple related tables (B) The dimension tables are normalized and stored as multiple related tables (C) Fact tables do not store any foreign keys or measurements (D) A fact table is connected to a set of dimension tables
Answer (1)
In a Snowflake schema, which is a type of database schema used in data warehouses, the primary focus is on organizing data in a normalized form to reduce redundancy and improve data integrity. The correct option for the question regarding the Snowflake schema is (B) The dimension tables are normalized and stored as multiple related tables.
Let's explain in more detail:
Definition : A Snowflake schema is an extension of the Star schema. It incorporates additional levels of normalization by splitting dimension tables into multiple related tables.
Normalization : In a Snowflake schema, dimension tables are normalized by removing redundancy and forming smaller tables. This process minimizes data duplication and strengthens data integrity, as related data is connected via relationships rather than repeating information.
Fact and Dimension Tables :
Fact Tables : These remain usually unnormalized in a Snowflake schema and store quantitative data for analysis, such as sales numbers or financial figures. Fact tables are linked to dimension tables via foreign keys.
Dimension Tables : These provide the 'context' for facts and are normalized in a Snowflake schema to reduce data redundancy. For example, a dimension such as 'Employee' might be split into 'Employee_Details' and 'Employee_Contact' tables, where each dimension table handles specific aspects and is linked to others through keys.
Usage : The Snowflake schema is useful in scenarios where data storage optimization is crucial and complex queries are frequently performed, making it easier to manage changes in dimensions without affecting the entire data warehouse.
By choosing option (B), we acknowledge the essence of a Snowflake schema in implementing a logical design framework that efficiently organizes data through normalization of the dimension tables.
