SYM-408, DQ1. 100-150 words
In a star schema model, explain, with examples, the differences between surrogate keys and natural keys. Why do we need both keys in a star schema model?
REPLIES 75-100 WORDS
A Trevor Stoutt
A star schema model has two types of keys: surrogate keys and natural keys.
Surrogate keys are identifier keys that are assigned to each record in a dimension table. They are used as primary keys in the star schema model. For example, a product dimension table may have a surrogate key for each product, such as 4, 5, 6. Natural keys are real-world keys that exist in the data and have meaning for each number. For example, a product dimension table may have a natural key for each product, such as numbers on a barcode or a HU for a warehouse batch label.
Both surrogate keys and natural keys are used in a star schema model because they have different roles. Surrogate keys are used to ensure unique and stable identifier for each record in the dimension table, while natural keys are used to provide meaningful business information and to maintain the relationship between the fact table and the dimension table (Varshney, 2023).
B Joshua Victor
A surrogate key is a unique identifier that is assigned to each record in a dimension table. It is a synthetic key made for the sole purpose of identifying records in the data in a singular way. The surrogate key functions as a foreign key in the fact table and as a primary key in the dimension table. A product ID might be used as a substitute key, for instance, in a table of product dimensions while a natural key is an unique identifier derived from the values of the data in a dimension table. It is a key that is already exists in the data and was not made with the intention of being used to identify entries. A product code or product name, for instance, could be used as a natural key in a table of product dimensions.
The reason as to why we need both keys in a star schema model is because they both keys are used to distinguish records in the data and link the fact table to the dimension tables in the star schema model. The surrogate key offers a distinctive identification that is constant and reliable even when the data in the dimension table changes, while the natural key offers a useful identifier that can be quickly recognized and understood by the data’s users.
C Prof Perez
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