Besides using _ID to do searching, you can also use other fields or multiple fields to do searching. For example: Examples JavaScript Codes By username   db.collection(“comments”).find( {username: “Peter”} , {limit: 1000}).asArray()   It will search all comments with username = “Peter”   By Date   db.collection(“comments”).find( { date: “01/01/2018”} , {limit: 1000}).asArray()   It