The star schema sometimes also called as star join schema is the modeling approach in dimensional modeling of Data warehouse. It contains one or more fact table and more than one dimension table. Dimension tables are joined to fact table by one-to-many relationship which forms a star like structure and that’s why this schema is called as star schema.
(Ref: Call Center Datawarehoue)
Star Schema is highly de-normalized and has its own benefits in datawarehouse environment.
1. Now a days most of the database optimizers use star transformations which uses Bitmap Indexes for fast predicate resolution, which helps to select particular record without hitting the fact table until the selections is resolved, which gives a very good performance gain.
2. Using partitioning features to gain performance is very easy in star schema as , one need to partition only Fact table also Optimizer can simply ignore other partition if they exist which saves lot of IO cycles.
3. Implementing slowly changing Dimensions is easy in star schema as compared to snowflake schema.
4. If your operation team writes lots of SQL to get required data out of database then they will love the star schema as its easy to understand and query does not require complex joins.
5. Implementing a complete BI solution using commercial tools like Business Objects, Cognos is easy with Star Schema and easy to maintain.
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