       ON UPDATE NO ACTION ON DELETE NO ACTION,
   CONSTRAINT fk_graph_uri FOREIGN KEY (graph_uri)
       REFERENCES wb_strings (id_string) MATCH SIMPLE
-      ON UPDATE NO ACTION ON DELETE NO ACTION
+      ON UPDATE NO ACTION ON DELETE NO ACTION,
+  CONSTRAINT uq_ver_uri UNIQUE (graph_version, graph_uri)
 )
 WITH (
   OIDS=FALSE

  ON wb_strings
  USING btree
  (id_string, string);




  USING btree
  (id_object, obj_type, obj_value);

CREATE INDEX idx_o_all
  ON wb_objects
  USING btree
  (obj_type, obj_value, obj_lang, obj_datatype, id_object);


-- Index: idx_vo

-- DROP INDEX idx_vo;
