Thursday 27 August 2015

Difference between star schema and snow flake schema?

Star Schema: 

In a star schema, the fact table will be at center and in connected to dimensional tables. The tables are completely in De normalized Structure. SQL queries performance in good as there are less number of joins involved. Data redundancy is high and occupies more disk spaces. 

Snowflake Schema:

 is an extension of star schema where the dimension tables are further connected to one or more dimensions. The tables are partially de normalized in structure. The performance of SQL queries is little bit less compared to star schema as more no. of joins are involved. Data redundancy is low and occupies less disk space compared to star schema.

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