Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{_id:ObjectId("5fedda064c9073b6289e8eaf")},{_id:ObjectId("6398c34ca67dbe3286452f23")}]
Query
db.collection.find({},{type:"$_id",_id:0})
Result