Database
db={"accounts":[{"_id":1,"accountId":"ac1"},{"_id":2,"accountId":"ac2"},{"_id":3,"accountId":"ac3"}],"list":[{"_id":1,"accountId":"ac1"},{"_id":2,"accountId":"ac2"},{"_id":4,"accountId":"ac4"}]}
Query
db.accounts.aggregate([{"$lookup":{"from":"list","localField":"accountId","foreignField":"accountId",pipeline:[{$limit:1}],"as":"listLookup"}},{$match:{listLookup:{$ne:[]}}}])