@@ -22,7 +22,9 @@ const (

         CONSTRAINT "parent_fk" FOREIGN KEY ("parent_id") REFERENCES "entity" ("id"),

         CONSTRAINT "entity_fk" FOREIGN KEY ("entity_id") REFERENCES "entity" ("id")

         );

+    `

+	createEdgeIndices = `

     CREATE UNIQUE INDEX "name_parent_ix" ON "edge" (parent_id, name);

     `

 )

@@ -67,6 +69,9 @@ func NewDatabase(dbPath string) (*Database, error) {

 	if _, err := conn.Exec(createEdgeTable); err != nil {

 		return nil, err

 	}

+	if _, err := conn.Exec(createEdgeIndices); err != nil {

+		return nil, err

+	}

 	rollback := func() {

 		conn.Exec("ROLLBACK")

@@ -59,6 +59,18 @@ func TestSetEntityWithDifferentName(t *testing.T) {

 	}

 }

+func TestSetDuplicateEntity(t *testing.T) {

+	db := newTestDb(t)

+	defer destroyTestDb(db)

+

+	if _, err := db.Set("/foo", "42"); err != nil {

+		t.Fatal(err)

+	}

+	if _, err := db.Set("/foo", "43"); err == nil {

+		t.Fatalf("Creating an entry with a duplciate path did not cause an error")

+	}

+}

+

 func TestCreateChild(t *testing.T) {

 	db := newTestDb(t)

 	defer destroyTestDb(db)