What are two consequences of changing the cardinality between two data extensions inside Contact Builder?

The choice regarding the review of all scheduled sends that utilize a filter based on one of the data extensions is correct because changing the cardinality between data extensions can significantly impact how data is related and utilized in the system. Cardinality defines the relationship between records in the data extensions; for instance, changing from one-to-many to many-to-one relationships will modify how records are matched and filtered.

When cardinality is altered, it is essential to review any scheduled sends as these may rely on filters that assume a specific relationship structure between the data extensions. If these filters are based on assumptions about the cardinality that no longer hold true after the change, it could lead to unexpected results, such as incorrect audience targeting or missing contacts that should be included in the send. Hence, a thorough review is necessary to ensure that the filters still function as intended and deliver the expected outcomes.

This understanding emphasizes the importance of maintaining data integrity and accuracy in any marketing or communication strategy that relies on targeted audiences defined by these filters.