Fear not: I've got you, as they say. Cardinality's official, non-database dictionary definition is mathematical: the number of values in a set. When applied to databases, the meaning is a bit different: it's the number of distinct values in a table column relative to the number of rows in the table. Repeated values in the column don't. 2022. 7. 28. · Relationships in Tableau have grown older – it’s been almost two years now when they started seeing the light of day. And still, even after all that time, there are many questions around this data model, be it within the Tableau Community, be it in Tableau trainings or be it with clients who have been really comfortable with joins and blends in the old data model. Tableau first attempts to create the relationship based on existing key constraints and matching field names. You can then check to ensure they are the fields you want to use, or add more field pairs to better define how the tables should be related. Automatic and context-aware. Relationships defer joins to the time and context of analysis.