Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{name:"a"},{name:"b"},{name:"c"},{name:"d"},{name:"e"}]
Query
db.collection.aggregate([{$sort:{name:1}},{$limit:3},{$addFields:{active:true}},{$merge:{into:"Test",on:"_id",whenMatched:"merge"}}])
Result