Discovering relations between JDBC Sources
JDBC objects are sourced from relational databases and so already have primary and foreign key relations defined. In Qlik Catalog. Through discovery and ingest, information about these relationships is fetched and retained as part of the source, entity, field metadata. For JDBC sources, users can drill into Field Information to see which fields are primary "Key" fields and which are "Foreign Key" fields. Note that while relations are fetched for both internal (discover) and external (source) objects, discover Field Information does not display Key and Foreign Key details in Field Information, General Information tab (though Lineage tab captures the relationship in both discover and source modules).
The following example illustrates how primary Key and Foreign Key fields are identified in the source module.
Select 
(view details) icon on the field row to access Field Information: General Information tab
Primary and Foreign key fields can be selected or will be checked to indicate primary and foreign key status: example of primary key field
Primary and Foreign key fields can be selected or will be checked to indicate primary and foreign key status: example of foreign key field
If two entities discovered have a foreign key relation between them, the relationship is persisted as a lineage relation with type FOREIGN_KEY in Lineage tab.
Persisted relations are informative for creation of dataflows in Prepare.
Once the entity or entities have been added to the canvas, SAVE the dataflow, select RECOMMENDATIONS to view DESIGN TIPS.Message example: "The entity <source1>.<entity1> has a foreign key relation with entity <source1>.<entity2>. You can join them using a Joiner on condition <entity1>.<foreignkey>=<entity2><primarykey>.
