4.Explain Snowflkeschema ?
Answer Posted / prodyot sarkar
A snowflake schema is a variation on the star schema, in which very large dimension tables are normalized into multiple tables. Dimensions with hierarchies can be decomposed into a snowflake structure when you want to avoid joins to big dimension tables when you are using an aggregate of the fact table. For example, if you have brand information that you want to separate out from a product dimension table, you can create a brand snowflake that consists of a single row for each brand and that contains significantly fewer rows than the product dimension table.
Advantages of Using the Snowflake Schema
i)in some cases may improve performance because smaller tables are joined,
ii)is easier to maintain
iii)increases flexibility.
Disadvantages of Using the Snowflake Schema
i)increases the number of tables an end-user must work with
ii)makes the queries much more difficult to create because more tables need to be joined.
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