Girinath.S.V.S

• Mar 17th, 2005

 

Snowflake schemas normalize dimensions to eliminate redundancy. That is, the dimension data has been grouped into multiple tables instead of one large table. For example, a product dimension table in a star schema might be normalized into a products table, a product_category table, and a product_manufacturer table in a snowflake schema. While this saves space, it increases the number of dimension tables and requires more foreign key joins. The result is more complex queries and reduced query performance

senkumar79

 Profile Answers by senkumar79 Questions by senkumar79

• Oct 4th, 2005

 

A normalised form of star schema is called snow flake schema.

Ramky18

 Profile Answers by Ramky18 Questions by Ramky18

• Oct 10th, 2005

 

The snowflake schema is an extension of the star schema, where each point of the star explodes into more points. The main advantage of the snowflake schema is the improvement in query performance due to minimized disk storage requirements and joining smaller lookup tables. The main disadvantage of the snowflake schema is the additional maintenance efforts needed due to the increase number of lookup tables.

Siva K

• Dec 14th, 2005

 

Some people are considering as Normalized star schema, but it is partially normalized star schema.  By partially normalizing it we may save some disk space.

sithusithu

 Profile Answers by sithusithu 

• Jan 9th, 2006

 

Star schema

A single fact table with N number of Dimension

 

Snowflake schema

Any dimensions with extended dimensions are know as snowflake schema

 

Multiple Star (galaxy)

If the schema has more than one fact table then the schema is said to be Multiple star

 

Cheers,

Sithu

bhawesh

• Jul 19th, 2007

 

The snowflake schema is a method of storing data which are multidimensional in nature (i.e. which can be analysed by any or all of a number of independent factors) in a  RDBMS.

It is a variation of star schema.


Snowflake schema consist of one Fact table connected to multiple dimension tables.


All the tables that describes dimensions of Snowflake schema must be in 3 NF.

jyotsna

• Sep 6th, 2007

 

Any schema with extended dimensions(ie., dimesion with one or more extensions) is known as snowflake schema

harshadapj

 Profile Answers by harshadapj 

• Jul 22nd, 2008

 

Closely related to the star schema, the snowflake schema is represented by centralized fact tables which are connected to multiple dimensions

In the snowflake schema, however, dimensions are normalized into multiple related tables whereas the star schema's dimensions are denormalized with each dimension being represented by a single table.

prodyot.sarkar

 Profile Answers by prodyot.sarkar 

• May 13th, 2010

 

Snow-flake schema is a logical arrangement of tables in dimensional modeling where a centralized fact table references number of other dimension tables; however, those dimension tables are further normalized into multiple related tables. Consider a fact table that stores sales quantity for each product and customer on a certain time. Sales quantity will be the measure here and keys from customer, product and time dimension tables will flow into the fact table. Additionally all the products can be further grouped under different product families stored in a different table so that primary key of product family tables also goes into the product table as a foreign key. Such construct will be called a snow-flake schema as product table is further snow-flaked into product family.

Example :

Dimension table (Customer, Product , Product_Family ,Time)

Customer
_______________
Cust-Key
Cust-name
Cust-Address
Cust-Status
....
....
....

Product
_______________
Prod-Key
Prod-Family-Key
Prod-Name
Prod-Category
Prod-price
....
....

Product_Family
_______________
Prod-Family-Key
Prod-Family-Name
Prod-Family-Desc
....
....

Time
_______________
Time-Key
Date
Month
Year

Fact table
_______________
Time-Key
Cust-key
Prod-Key
Quantity
....
....

       Customer ---- Fact table ---- Product----Product_Family
                                      |
                                      |
                                   Time

Snow-flake increases degree of normalization in the design.