For example, the topic contains a Customer table and a Business Unit table. A customer can belong to more than one business unit. You create a subscription that subscribes to both tables in the topic, and add a filter to the Business Unit table to consume the data for a single business unit. Using the relationship information between the tables, the filter is implicitly applied to the customers table, and the subscriber consumes only the data for customers that belong to the business unit that interests you.

You define the relations between topic tables by assigning primary and foreign keys to the relevant tables. In our example, you define a column in the Business Unit as a primary key, and one or more columns in the Customer table as foreign keys.