Make Relationship Cardinality Explicit

[mullinsms]

OSI models relationships primarily through join keys (entities) and inferred join behavior. This works well for many star-schema cases, but it leaves key relationship semantics implicit, which can make SQL generation and portability across semantic layers (e.g., Coginiti, Cube, AtScale, BI tools) either lossy or error-prone.

Suggested enhancement
Introduce an optional relationship block (or relationship annotations) that can be attached to an entity pair / join key mapping, such as: cardinality: one_to_one | one_to_many | many_to_one | many_to_many

[PioMen]

To your point, maybe this should be even extended by custom joining criteria? Currently there is from_column and to_column. In some joins you need to add custom logic (like join on pk + date (either current or between other dates).