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Box 1: Assume Referential Integrity
When connecting to a data source using DirectQuery, you can use the Assume Referential Integrity selection to enable running more efficient queries against your data source. This feature has a few requirements of the underlying data, and it is only available when using DirectQuery.
Note: The following requirements are necessary for Assume referential integrity to work properly:
Data in the From column in the relationship is never Null or blank
For each value in the From column, there is a corresponding value in the To column
Box 2: Star schema -
Star schema is a mature modeling approach widely adopted by relational data warehouses. It requires modelers to classify their model tables as either dimension or fact.
Generally, dimension tables contain a relatively small number of rows. Fact tables, on the other hand, can contain a very large number of rows and continue to grow over time.
Example:
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Reference:
https://docs.microsoft.com/en-us/power-bi/connect-data/desktop-assume-referential-integrity https://docs.microsoft.com/en-us/power-bi/guidance/star-schema