Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{price:{v1:50,v2:null}},{price:{v1:null,v2:25}},{price:{v1:30,v2:25}}]
Query
db.collection.aggregate([{$match:{$expr:{$gt:[{$ifNull:["$price.v2","$price.v1"]},20]}}}])
Result