Deeptiman

[
  {
    "_id": "573a1390f29313caabcd6223",
    "comments": [
      {
        "_id": "5a9427648b0beebeb69579cc",
        "comment": "Rem officiis eaque repellendus amet eos doloribus. Porro dolor voluptatum voluptates neque culpa molestias. Voluptate unde nulla temporibus ullam.",
        "date": "2012-03-26T05:30:00+05:30",
        "email": "andrea_le@fakegmail.com",
        "movie_id": "573a1390f29313caabcd6223",

Deeptiman

[
  {
    "_id": "573a1390f29313caabcd6223",
    "comments": [
      {
        "_id": "5a9427648b0beebeb69579cc",
        "comment": "Rem officiis eaque repellendus amet eos doloribus. Porro dolor voluptatum voluptates neque culpa molestias. Voluptate unde nulla temporibus ullam.",
        "date": "2012-03-26T05:30:00+05:30",
        "email": "andrea_le@fakegmail.com",
        "movie_id": "573a1390f29313caabcd6223",

Deeptiman

{
        $lookup:
            {
                from: <collection to join>,
                localField: <field from the input documents>,
                foreignField: <field from the documents of the "from" collection>,
                as: <output array field>
            }
 }

Deeptiman

{ 
    "_id" : "total_vote", 
    "vote_count" : NumberInt(271026594)
}

Deeptiman

db.movies.aggregate(
        // Pipeline
        [
            // Stage 1
            {
                $match: {
                    // conditional query 
                    "imdb.rating": {
                        $lt: 7.5
                    }

Deeptiman

{ 
        "_id" : 1.0, 
        "value" : 271026594.0
}

Deeptiman

db.movies.mapReduce(
        // map
        function(){
            emit(1,this.imdb.votes);
        }, 

        // reduce
        function(key,vals){ 
            var count = 0;
            vals.forEach(function(v) {

Deeptiman

[{ 
    "email" : "andrea_le@fakegmail.com", 
    "name" : "Andrea Le"
},
{ 
    "email" : "anthony_cline@fakegmail.com", 
    "name" : "Anthony Cline"
},
{ 
    "email" : "emily_ellis@fakegmail.com", 

Deeptiman

db.user_data_list.find({})

Deeptiman

{ 
    "ok" : 1.0
}