Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{_id:"xyz",p1:"A",p2:"E",p3:"C"},{_id:"def",p1:"A1",p2:"E1",p3:"C1"}]
Query
db.collection.aggregate([{$project:{p:["$p1","$p2","$p3"]}}])
Result