$ lookup并插入golang

Question

How can I write a similar query in golang (mgo)?

db.result.aggregate([{
    $lookup: {
        from: "session",
        localField: "session.id",
        foreignField: "_id",
    as: "session_info"
    }
}]).forEach(function(d){db.result.insert(d)})

First I have got this, but I don't know how to insert the result into the same collection...

var results []AggregateData
    pipe := d.Pipe([]bson.M{
        bson.M{"$lookup": bson.M{
            "from": "session",
            "localField": "session.id",
            "foreignField": "_id",
            "as": "session_info",
        }},
    }).All(&results)

Maybe I could iterate over the results and insert it into the collection, but it would slow down my application.