https://github.com/bobthecow/genghis

目前觉得挺赞的 试用到现在有个问题有待解决，请高手搞定吧

**Notice: C extension not loaded. This is required for optimum MongoDB Ruby driver performance.
  You can install the extension as follows:
  gem install bson_ext

  If you continue to receive this message after installing, make sure that the
  bson_ext gem is in your load path and that the bson_ext and mongo gems are of the same version.

不过不影响使用