code: public int count() {
  		Integer result = null;
  		if (result == null) {
  			SimpleQuery q = this.isKeysOnly()? this : this.clone().keysOnly();
  			result = getDatastoreService().prepare(q.getQuery()).countEntities(fetchOptions);
  		}
  		return result;
  	}
docs: Counts the number of instances returned from this query. This method will only
  retrieve the matching keys, not the entities themselves.