class ResultSets {

    public static List<ListenableFuture<ResultSet>> queryAll(Session session, String query, Object... partitionKeys) {
        List<ResultSetFuture> futures = sendQueries(session, query, partitionKeys);
        //原先List里是ResultSetFuture, Future里是ResultSet: ResultSetFuture<ResultSet>,
        //将ResultSetFuture转换为可监听的ListenableFuture, 结果还是ResultSet.
        return Futures.inCompletionOrder(futures);
    }

}