Mongoose limit/offset and count query

I suggest you to use 2 queries:

1. db.collection.count() will return total number of items. This value is stored somewhere in Mongo and it is not calculated.

2. db.collection.find().skip(20).limit(10) here I assume you could use a sort by some field, so do not forget to add an index on this field. This query will be fast too.

I think that you shouldn't query all items and than perform skip and take, cause later when you have big data you will have problems with data transferring and processing.

Instead of using 2 separate queries, you can use aggregate() in a single query:

Aggregate "$facet" can be fetch more quickly, the Total Count and the Data with skip & limit

    db.collection.aggregate([

      //{$sort: {...}}

      //{$match:{...}}

      {$facet:{

        "stage1" : [ {"$group": {_id:null, count:{$sum:1}}} ],

        "stage2" : [ { "$skip": 0}, {"$limit": 2} ]
  
      }},
     
     {$unwind: "$stage1"},
  
      //output projection
     {$project:{
        count: "$stage1.count",
        data: "$stage2"
     }}

 ]);

output as follows:-

[{
     count: 50,
     data: [
        {...},
        {...}
      ]
 }]

Also, have a look at https://docs.mongodb.com/manual/reference/operator/aggregation/facet/