how to flat result after mongodb mapreduce

问题

After playing with MapReduce with MongoDB,

The documents look like:

{_id: { somecola : 123, somecolb : 456 }, value:10 }

I want this format:

{ _id : somerandomcode, somecola : 123, somecolb : 456, value :10 }

Creating a new collection, and foreach + insert can do it but it is too slow, how to do it rapidly?

Thanks

来源：https://stackoverflow.com/questions/14574262/how-to-flat-result-after-mongodb-mapreduce