Codeigniter извлекает большие данные для данных не работает

Question

Я пытаюсь добавить данные в подключаемый модуль, используя codeigniter, но объем данных увеличивается.поэтому время загрузки моей страницы очень велико.поэтому я хочу получать постраничные данные из базы данных.

мой php view

<table class="table table-bordered table-striped" id="userTbl">
    <thead>
    <th>Sr no</th>
    <th>UserId</th>
    <th>Name</th>
    <th>Mobile No.</th>
</thead>
</table>
<script>
    fetch_data('no');
    function fetch_data(is_date_search, start_date = '', end_date = '')
    {
        dataTable = $('#userTbl').DataTable({
            language: {search: ""},
            "processing": true,
            "serverSide": true,
            "order": [[0, "desc"]],
            "ajax": {
                url: "<?php echo site_url(); ?>/Admin/users_table",
                type: "POST",
                data: {
                    is_date_search: is_date_search, start_date: start_date, end_date: end_date
                }
            },
            responsive: true,
            "lengthMenu": [[10, 25, 50, -1], [10, 25, 50, "All"]], // page length options
            "dom": 'Bfrtip',
            "buttons": ['pageLength', $.extend(true, {}, {
                    extend: 'excelHtml5',
                    title: 'users'
                }), ],

        });

        $('#userTbl_filter input[type="search"]').attr('placeholder', 'Search');
        $("#userTbl_filter").addClass('col-sm-2 temp');
        $("#userTbl_length").addClass('col-sm-2');

        var div = document.createElement('div');
        // set class name
        div.className = 'col-sm-8 sf';
        // set html contents
        div.innerHTML = '<form name="form1" method="POST" action=""><div class="col-sm-4 no-padding padd"><input class="form-control" id="from_date" name="from_date" placeholder="Form Date" type="text" style="width:48%;display:inline;margin-right: 8px;" value="<?php echo set_value('from_date'); ?>" /><input class="form-control" id="to_date" name="to_date" placeholder="To Date" type="text" style="width:48%;display:inline;" value="<?php echo set_value('to_date'); ?>" /><span class="text-red"><?php echo validation_errors(); ?></span></div><div class="col-sm-2 no-padding padd"><button type="button" id="mybutton" class="form-control fa fa-search btn btn-default" style="width:auto;">&nbsp;Search</button></div></form>';

        // get .div2 element
        var ele = document.querySelector('.temp');

        ele.parentNode.insertBefore(div, ele);
        $("#from_date").datepicker({format: 'dd-mm-yyyy'});
        $("#to_date").datepicker({format: 'dd-mm-yyyy'});

        $('#mybutton').click(function () {

            var start_date = $('#from_date').val();
            var end_date = $('#to_date').val();
            if (start_date != '' || end_date != '')
            {
                $('#userTbl').DataTable().destroy();
                fetch_data('yes', start_date, end_date);
            } else
            {
                window.location.reload();
            }
        });
        if (start_date != '') {
            $('#from_date').val(start_date);
        }
        if (end_date != '') {
            $('#to_date').val(end_date);
    }
    }

</script>

и мой контроллер

$requestData = $_REQUEST;
        $columns = array(
            0 => 'user_id',1 => 'user_id',2 => 'user_name',3 => 'user_mobile', 
        );
        $sql = "SELECT *  FROM `tbl_users`";
        $query = $this->db->query($sql);
        $totalData = $query->num_rows();
        $totalFiltered = $totalData;  
        if (strtolower($requestData["search"]["value"]) == 'active') {
            $search_term = 1;
        } else if (strtolower($requestData["search"]["value"]) == 'deactive') {
            $search_term = 0;
        } else {
            $search_term = $requestData["search"]["value"];
        }
        $sql = "SELECT *  FROM `tbl_users` WHERE 1=1 ";
        if (!empty($requestData['search']['value'])) {  
            $sql .= 'AND (user_id LIKE "%' . $requestData["search"]["value"] . '%" 
    OR user_name LIKE "%' . $requestData["search"]["value"] . '%"';}
        $query = $this->db->query($sql);
        $totalFiltered = $query->num_rows(); 
        if ($requestData['start'] == 0 && $requestData['length'] == -1) {
            $sql .= " ORDER BY user_id DESC ";
        } else {
            if (isset($requestData["order"])) {
                $sql .= "  ORDER BY " . $columns[$requestData['order'][0]['column']] . "   " . $requestData['order'][0]['dir'] . "  LIMIT " . $requestData['start'] . " ," . $requestData['length'] . "   ";
            } else {
                $sql .= " ORDER BY user_id DESC  LIMIT " . $requestData['start'] . " ," . $requestData['length'] . "   ";
            }
        }
        $query = $this->db->query($sql)->result_array();
        $data = array();
        $i = 1 + $requestData['start'];
        foreach ($query as $row):
            $nestedData = array();
            $nestedData[] = $i;
            $nestedData[] = $row['user_id'];
            $nestedData[] = $row['user_name'];
            $nestedData[] = $row["user_mobile"];
            $data[] = $nestedData;
            $i++;
        endforeach;
        $json_data = array(
            "draw" => intval($requestData['draw']),
            "recordsTotal" => intval($totalData),
            "recordsFiltered" => intval($totalFiltered), 
            "data" => $data 
        );
        echo json_encode($json_data);

Извините за длинный код.я новичок в codeigniter Framework я пытаюсь отправить стартовый индекс и предел, но это не работает.