MongoDB ?? 2.4?? Aggregat(), Pineline() ????? ??? ???, ?? 2.0.6?? Aggregat ???? ?? ??? ? ??? ?? 2.0.6?? ???? ?????. ???? ?? ?? ??? ???? ??? ?????? group() ???? ???? ???.
Aggregation? 2.2? ??? ??? ?????. ?? ????? Map/Reduce? ???????.