+ self.table_name = "relation_tags"
+ self.primary_keys = "relation_id", "version", "k"
+
+ belongs_to :old_relation, :foreign_key => [:relation_id, :version]
+
+ validates :old_relation, :presence => true, :associated => true
+ validates :k, :v, :allow_blank => true, :length => { :maximum => 255 }
+ validates :k, :uniqueness => { :scope => [:relation_id, :version] }