Codeigniter active records query taking too much t

Question

I'm using codeigniter

This is my model

<?php

class groups_Model extends CI_Model {
    public function __construct(){
        parent::__construct();
    }
    /**
     * get All groups
     * @return array object list of groups
     */
    public function get(){
        $this->db->select('groups.id,groups.name as group,status.name as status');
        $this->db->from('groups');
        $this->db->join('status', 'status.id = groups.status');
        $this->db->order_by('groups.id', 'ASC');
        $this->db->limit($this->config->item('per_page'),$this->uri->segment(4));

        $query = $this->db->get();
        $total = $query->num_rows();
        if($total > 0){
            return $query->result();
        }
        return false;
    }

?>  

Now i have 500000 dummy records in my database
I'm fetching 20 records using pagination
but my query take 5 to 6 seconds how to speed up database performance

controller code look like this

<?php

public function groups(){
    $this->output->enable_profiler(TRUE);
    $this->benchmark->mark('code_start');
    $this->output->cache(5);
    $this->load->model('groups_Model');
    $this->load->library('pagination');
    $this->config->load('pagination');
    $config['base_url'] = base_url().'admin/auth/groups';
    $config['total_rows'] =$this->groups_Model->count(null);
    $this->pagination->initialize($config);
    $data['groupsList']=$this->groups_Model->get();
    $this->load->view('admin/templates/header');
    $this->load->view('admin/groups',$data);
    $this->load->view('admin/templates/footer');
    $this->benchmark->mark('code_end');
    echo $this->benchmark->elapsed_time('code_start', 'code_end');
}
?>  

All queries taking this much time to run

  DATABASE:  database_name (Auth:$db)   QUERIES: 5 (5.8955 seconds)  (Hide)
1.6279      SELECT * FROM groups 
4.2598      SELECT `groups`.`id`, `groups`.`name` as `group`, `status`.`name` as `status`
FROM `groups`
JOIN `status` ON `status`.`id` = `groups`.`status`
ORDER BY `groups`.`id` ASC
 LIMIT 40, 20 
0.0078      SELECT `username`
FROM `users`
WHERE `id` = '1' 
0.0000      SELECT `first_name`
FROM `users`
WHERE `id` = '1' 
0.0000      SELECT `last_name`
FROM `users`
WHERE `id` = '1' 

Answer 1

Use pagination this is the best way to use it

create these to function in model

Model

public function get_count($table){
        return $this->db->count_all_results($table);
    }

    public function get_all_userdata($table, $where, $limit, $start){
        $query = $this->db->get_where($table, $where, $limit, $start);
        $data = $query->result_array();
        return $data;
    }

Controller

$where = array('status' => 0);
         //pagination
        $config['base_url'] = base_url('nonactiveusers');
        $config['total_rows'] =  $this->User_model->get_count();
        $config['per_page'] = 5;
        $config["num_links"] = 3;
        $config['uri_segment'] = 2;

        $config['full_tag_open'] = "<ul class='pagination'>";
        $config['full_tag_close'] ="</ul>";
        $config['num_tag_open'] = '<li>';
        $config['num_tag_close'] = '</li>';
        $config['cur_tag_open'] = "<li class='disabled'><li class='active'><a href='#'>";
        $config['cur_tag_close'] = "<span class='sr-only'></span></a></li>";
        $config['next_tag_open'] = "<li>";
        $config['next_tag_close'] = "</li>";
        $config['prev_tag_open'] = "<li>";
        $config['prev_tag_close'] = "</li>";
        $config['first_tag_open'] = "<li>";
        $config['first_tag_close'] = "</li>";
        $config['last_tag_open'] = "<li>";
        $config['last_tag_close'] = "</li>";

        $config['first_link'] = "<<";
        $config['last_link'] = ">>";


        $this->pagination->initialize($config);
        $page = $this->uri->segment(3); // your uri segment here
        $data['links'] = $this->pagination->create_links();
        $result = $this->User_model->get_all_userdata("users", $where, $config['per_page'], $page);

        $data['users'] = $result;
        $this->load->view('view', $data);

Answer 2

$total = $query->num_rows();  
$total = $this->db->count_all_results($table);

The last one will give you faster result, because it only return count result. The first one (yours) is slower because it is also return the result.