Ruby on Rails 3: How to use MapReduce with the MongoDB Ruby driver?

How can I use MapReduce in Ruby on Rails if I'm using the MongoDB Ruby 开发者_开发百科driver?

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Define your map and reduce js functions as variables, and then something along these lines:

activities = Connection.new(host,port).db(dbname).collection('activities')
activities.mapreduce(map,reduce,:out=>'analytics')

The 'analytics' collection will hold the result of the mapreduce operation.