@baris Hm was doing similar approach, please check my another question with path.js error.
I will answer myself on question. 😉
You need to remove these documents (_key pattern) from objects collection:
* where numbers are identifiers
Or if you don't want to do it manually, you could wait for future NodeBB Utils plugin:
Screen Shot 2015-10-14 at 11.55.39 PM.png