db={"documents":[{"_id":1,"name":"test","author_id":1},{"_id":2,"item":"test 2","author_id":2},],"author":[{"_id":1,"first_name":"Junior","last_name":"Neymar","address":"Brazil","is_deleted":false},{"_id":2,"first_name":"cristiano","last_name":"Ronaldo","address":"Protugal","is_deleted":true}]}

db.documents.aggregate([{$lookup:{from:"author",localField:"author_id",foreignField:"_id",pipeline:[{$match:{"is_deleted":false}}],as:"author_id",}},{"$unwind":"$author_id"},{$project:{author_id:0}},{$skip:0},{$limit:2}])