Star schema :-
A logical structure that has a fact table containing factual data in the center, surrounded by dimension tables containing reference data, which can be denormalized
Advantage
Improve query performance for often-used data
Easy to define
Reduces number of physical joins
Disadvantage
High overhead of redundant data
Inappropriate when additional data is not accessed often.
Snowflake schema
A variant of the star schema where dimension tables do not contain denormalized data
It allows dimensions to have dimensions
Advantage
Provides best performance when queries involve aggregation
Disadvantage
Maintenance is complicated
Number of tables involve are more
More joins are needed
Starflake schema
A hybrid structure that contains a mixture of star and snowflake schema
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