Mongo: using aggregate to access page event meta data within XDB

aggregate.js

db.Interactions.aggregate([
     { "$match": { "StartDateTime": { $gte: ISODate("2015-11-01T00:00:00.000Z"),
                                      $lt: ISODate("2015-11-01T03:00:00.000Z")}}},
     { $project : { Pages : "$Pages" } },
     
     // Un-wind the array's to access filtering 
     { "$unwind": "$Pages" },
     { "$unwind": "$Pages.PageEvents" },
     // Group results to obtain the matched count per key
     { "$group": {
         "_id": "$Pages.PageEvents.Name",
         "count": { "$addToSet": "$Pages.PageEvents.Text" }
        }
     }
 ])