Cardinality in Tableau Semantics

Define how objects in your Semantic Layer relate to each other to ensure accurate results and faster queries. By setting cardinality, you tell Tableau Semantics how records from one object connect to records in another, helping the system optimize joins, reduce duplicate data, and improve the reliability of your metrics.

When you explicitly define these relationships, Tableau Semantics understands the structure of your data and chooses the most efficient way to process it. For example, you might want to analyze customer subscriptions:

• If every customer has exactly one subscription, defining a one-to-one relationship ensures that each customer record matches a single subscription record.
• If a customer can have multiple orders, a one-to-many relationship ensures that Tableau aggregates the orders without duplicating customer totals.

Cardinality also improves transparency and trust in your data models. By clearly defining how objects are connected, you make it easier to trace data lineage, audit results, and prevent modeling issues. For example, when working with Campaign Performance and Social Engagement data, setting the relationship to many-to-one ensures that multiple engagement records are tied to a single campaign, avoiding inflated counts during reporting.

Note Defining a one-to-one or many-to-one relationship disables the deduplication algorithm. Performance will improve, but if cardinality is set incorrectly it may cause row multiplication and lead to inaccurate results.

• Set Cardinality for Relationships
  Set the correct cardinality type to define how two objects are related and ensure Tableau Semantics interprets joins accurately. This helps prevent unexpected duplicates or missing data and improves overall query performance.