text: CREATE TABLE containers (
    id UUID,
  
    CONSTRAINT containers_key PRIMARY KEY ( id ),
    CONSTRAINT containers_ref_entities FOREIGN KEY ( id ) REFERENCES entities ( id )
  );
  
  CREATE TABLE container_members (
    container_id UUID,
    member       UUID,
  
    CONSTRAINT container_members_primary_key PRIMARY KEY (container_id, member),
    CONSTRAINT container_members_refs_containers FOREIGN KEY ( container_id ) REFERENCES containers ( id ),
    CONSTRAINT container_members_member_ref_entities FOREIGN KEY ( member ) REFERENCES entities ( id )
  );
  
  CREATE VIEW containers_join_entity AS
    SELECT e.*
      FROM containers c JOIN entities e ON c.id=e.id;
  