I have an idea.. but still not a compelling example for it.

metadata.js

var moment = require('moment');

TestObjectMeta = Parse.Object.extend("TestObject_meta");

Parse.Cloud.beforeSave("TestObject", function(request, response) {
  var obj = request.object;
  if (obj.isNew()) {
    var at = moment();
    var metadata = new TestObjectMeta();
    metadata.set('year', at.year());
    metadata.set('month', at.month());
    metadata.set('day', at.day());
    metadata.set('hour', at.hours());
    metadata.set('minute', at.minutes());
    metadata.set('second', at.seconds());
    metadata.set('user', request.user);
    metadata.save(null, { useMasterKey: true }).then(function() {
      obj.set('metadata', metadata);
      response.success();
    }, function(err) {
      response.error(err);
    });
  } else {
    response.success();
  }
});

Parse.Cloud.afterSave("TestObject", function(request) {
  var obj = request.object;
  if (!obj.existed()) {
    var metadata = obj.get('metadata');
    metadata.set('obj', obj);
    return metadata.save(null, { useMasterKey: true });
  }
});

Parse.Cloud.define('testQueryByDate', function(request, response) {
  var query = new Parse.Query("TestObject");
  query.greaterThanOrEqualTo('createdAt', new Date(2014, 7 - 1, 1));
  query.lessThan('createdAt', new Date(2014, 8 - 1, 1));
  query.find({ useMasterKey: true }).then(function(results) {
    response.success(results);
  }, function(error) {
    response.error(error);
  });
});

Parse.Cloud.define('testQueryByMetadata', function(request, response) {
  var query = new Parse.Query(TestObjectMeta);
  query.equalTo('year', 2014);
  query.equalTo('month', 7 - 1);
  query.include('obj');
  query.find({ useMasterKey: true }).then(function(results) {
    response.success(results);
  }, function(error) {
    response.error(error);
  });
});

However what about querying using get() with Parameter & useMasterKey Flag using Promises?

Parse.Cloud.define('testQueryByMetadata', function(request, response) { var query = new Parse.Query(TestObjectMeta); query.get({ useMasterKey: true }, request.user).then(function(results) { response.success(results); }, function(error) { response.error(error); }); });

var GameScore = Parse.Object.extend("GameScore"); var query = new Parse.Query(GameScore); query.get("xWMyZ4YEGZ", { useMasterKey : true, success: function(gameScore) { // The object was retrieved successfully. }, error: function(object, error) { // The object was not retrieved successfully. // error is a Parse.Error with an error code and message. } });