In Power BI, working with complex relationship-oriented calculations among different tables requires the application of appropriate primary and foreign keys with the right cardinality for accuracy and efficacy.
Establish Primary and Foreign Keys Correctly: Every table must have its distinct value as a primary key, and any other relevant tables must have the appropriate foreign keys. Usually, dimension tables are single-column primary keys that relate to their respective fact tables through one or more foreign keys, which creates clear, simple one-to-many relationships.
Choose the Suitable Cardinality: Relationships must be established with the relevant cardinalities as one-to-many and many-to-one relationships for good performance. Incorrect settings may lead to unwanted calculations that are wrong or filtering that is not decisive. One-to-many relationships are the most preferred as they enhance performance by reducing the filtering path. Do not embrace many-to-many relationships unless they are absolutely unavoidable since they present challenges in filtering and calculations.
Steer Clear of Bidirectional Filtering Unless There is a Compelling Reason: Complex models often suffer from containment issues if bidirectional filtering is implemented. It is advised that it be used responsibly where necessary and to its effect on performance. In place of this, bridge tables or DAX functions such as TREATAS or CROSSFILTER can be used to control a specific flow of filters without introducing bi-directionality.
Following these measures will allow for a workable model in which the minimization of the calculation problems nexus is clear and effective.
