In a QGIS 3.10 project, I’ve set up a relationship between two postgis table. In postgis, table A has two unique fields: “id” and “name”. “Id” is the primary key but “name” is used as a foreign key for table B as “name A”. In the QGIS project’s properties, I’ve set up the relation as so: Parent layer: layer A Referenced field: Name Child Layer: layer B Referencing field: Name A This works as …