Fetching data after a certain time interval(10 sec) from a continuously increasing database like mysql using flask

@app.route('/data', methods=['post'])
def data():
    all_the_data = Data.query.order_by(Data.created.desc()).all()
    return jsonify(results=all_the_data)

$.ajax({
    type: "POST",
    url: "/data",
    dataType: "json",
    success: function(data) { 
        console.log(data);
        update_graph(data);
    }
});

@app.route('/data', methods=['post'])
def data():
    client_data = request.json
    reference = client_data.get('reference')

    if reference:
        # we have a reference, so lets filter the query:
        query_data = Data.query.filter(Data.id>reference).order_by(Data.created.desc()).all()
    else:
        # no reference, so send the lot!
        query_data = Data.query.order_by(Data.created.desc()).all()

    return jsonify(results=query_data)

$.ajax({
    type: "POST",
    url: "/data",
    data: JSON.stringify({ reference: 999 }),
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function(data) {
       console.log(data)
       update_graph(data["results"]);
    }
});