belongs_to :current_relation, :class_name => "Relation", :foreign_key => "relation_id", :inverse_of => :old_relations
has_many :old_members, -> { order(:sequence_id) }, :class_name => "OldRelationMember", :foreign_key => [:relation_id, :version], :inverse_of => :old_relation
has_many :old_tags, :class_name => "OldRelationTag", :foreign_key => [:relation_id, :version], :inverse_of => :old_relation
belongs_to :current_relation, :class_name => "Relation", :foreign_key => "relation_id", :inverse_of => :old_relations
has_many :old_members, -> { order(:sequence_id) }, :class_name => "OldRelationMember", :foreign_key => [:relation_id, :version], :inverse_of => :old_relation
has_many :old_tags, :class_name => "OldRelationTag", :foreign_key => [:relation_id, :version], :inverse_of => :old_relation