Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{"key":1},{"key":2}]
Query
db.collection.aggregate([{$facet:{docs:[{$match:{}}],count:[{$count:"count"}]}},{$addFields:{count:{$arrayElemAt:["$count.count",0]}}}])
Result