[{"_id":1,"albums":[{"_id":ObjectId("4d3ed089fb60ab534684b7e0"),"name":"Violator","producer":"George Martin"}]},{"_id":2,"albums":[{"_id":"a1","name":"/","producer":"George Martin"},{"_id":"a2","name":"+","producer":"Another producer"}]}]

db.collection.aggregate([{"$match":{$expr:{$eq:[true,{"$reduce":{"input":"$albums","initialValue":true,"in":{$and:["$$value",{$eq:["$$this.producer","George Martin"]}]}}}]}}}])