Which types of relationships limit encrypted fields from being used effectively?

In Salesforce, when it comes to encrypted fields, the constraints around their usability are particularly influenced by the type of relationships between objects. Encrypted fields can indeed be used in both master-detail and lookup relationships, but there are specific limitations that come into play with master-detail relationships.

Master-detail relationships function with a tight coupling between the parent and child objects. In these relationships, the child’s lifecycle and ownership depend on the parent, and certain actions, like sharing and access settings, are dictated by the parent object. When using encrypted fields in a master-detail relationship, they cannot be used for certain operations that rely on the relationship's intrinsic properties. For instance, if the child record is encrypted, the parent cannot access that encrypted data directly, which severely limits how the data can be utilized in reports, formulas, and other features that require relational operations.

On the other hand, lookup relationships allow for more flexibility with data access and do not impose the same constraints as master-detail relationships. When encrypted fields are part of a lookup relationship, the usability remains intact because the lookup does not enforce the same level of dependency and access restrictions that a master-detail relationship does.

Thus, the conclusion is that master-detail relationships impose specific limitations on the effective use of encrypted fields,