Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{"key1":1,"key2":21},{"key1":2,"key2":232,"key3":232},{"key1":2,"key2":232,"key3":233}]
Query
db.collection.aggregate({$group:{_id:{key1:"$key1",key2:"$key2",},all:{$push:"$$ROOT"}}})
Result