Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{Name:"A",likes_count:3},{Name:"B",likes_count:2},{Name:"C",likes_count:1}]
Query
db.collection.aggregate([{$group:{_id:null,Totallikes:{$sum:"$likes_count"}}}])
Result