MongoDB 2.6 Aggregation framework improvements

MongoDB is evolving rapidly. The 2.2 version introduced the aggregation framework as an alternative to the Map-Reduce query model. Generating aggregated reports is a recurrent requirement for enterprise systems and MongoDB shines in this regard. If you’re new to it you might want to check this aggregation framework introductionor the performance tuning and the data modelling guides.

Let’s reuse the data model I first introduced while demonstrating the blazing fast MongoDB insert capabilities:

{
        "_id" : ObjectId("5298a5a03b3f4220588fe57c"),
        "created_on" : ISODate("2012-04-22T01:09:53Z"),
        "value" : 0.1647851116706831
}

MongoDB 2.6 Aggregation enhancements

In the 2.4 version, if I run the following aggregation query:

db.randomData.aggregate( [
{
    $match: {
        "created_on" : {
            $gte : new Date(Date.UTC(2012, 0, 1)),
            $lte : new Date(Date.UTC(2012, 0, 10))
        }
    }
},
{
    $group: {
        _id : {
            "minute" : {
                $minute : "$created_on"
            }
        },
        "values": {
            $addToSet: "$value"
        }
    }
}]);

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