Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{"A":{"_id":"ID0"},"B":[{"_id":"ID0","field":"X"},{"_id":"ID1","field":"Y"}]}]
Query
db.collection.aggregate([{$addFields:{"B":{$filter:{input:"$B",as:"arr",cond:{$eq:["$A._id","$$arr._id"]}}}}}])
Result