try {
  projects.each { node ->
    old_id = node.ref_id
    new_id = old_to_new_ids[old_id]
    index.remove('project', old_id, node)
    node.ref_id = new_id
    index.put('project', new_id, node)
  }
} catch (Throwable e) {
  println(e)
} finally {
  g.shutdown()
}

EmbeddedGraphDatabase db = new EmbeddedGraphDatabase(dbFilename);
Transaction tx = db.beginTx();
PropertyContainer properties = db.getNodeManager().getGraphProperties();
properties.setProperty("schema_version", 3);
tx.success();
tx.finish();