CodeIgniter count too slow – pagination

I’m trying to make a search using CodeIgniter faster. I use the pagination library and I have to count the records returned from the query on a table which contains more than 1.2 million records. The num_rows() function is very slow ( takes approximately 3 seconds )

public function search()
{
    $this->output->enable_profiler(TRUE);
    
    $data = array();
    
    $query = $this->input->get('query');
    $filter = $this->input->get('f');
    $hd = $this->input->get('hd');

    if($hd == 'true'):
        $this->db->where('hd',1);
    endif;

    $request = urldecode($query);
    
    $where = "MATCH (name,tags) AGAINST ('".$request."' IN BOOLEAN MODE)";
    $this->db->where($where);   

    $get_vars = $this->input->get();

    if(is_array($get_vars) && ($this->input->get('query')) ):
        $config['suffix'] = '?'.http_build_query($get_vars,'', '&');
    endif;

    $config['base_url'] = base_url('search');
    $config['per_page'] =  8;
    $config['num_links'] = 8;
    $config['full_tag_open'] = '<div class="pagination"><ul>';
    $config['full_tag_close'] = '</ul></div><!--pagination-->';
    $config['first_link'] = '&laquo; First';
    $config['first_tag_open'] = '<li class="prev page">';
    $config['first_tag_close'] = '</li>';
    $config['last_link'] = 'Last &raquo;';
    $config['last_tag_open'] = '<li class="next page">';
    $config['last_tag_close'] = '</li>';
    $config['next_link'] = 'Suivant &rarr;';
    $config['next_tag_open'] = '<li class="next page">';
    $config['next_tag_close'] = '</li>';
    $config['prev_link'] = '&larr; Précédent';
    $config['prev_tag_open'] = '<li class="prev page">';
    $config['prev_tag_close'] = '</li>';
    $config['cur_tag_open'] = '<li class="active"><a href="">';
    $config['cur_tag_close'] = '</a></li>';
    $config['num_tag_open'] = '<li class="page">';
    $config['num_tag_close'] = '</li>';
    
    $query = clone $this->db;
    $config['total_rows'] = $query->get('videos')->num_rows();      
    $config['segment'] = $this->uri->segment(2);
    $this->pagination->initialize($config);

    $data['results'] = $this->db->get('videos',$config['per_page'],$this->uri->segment(2))->result();

    $this->load->view('search',$data);
}

Any solutions?

Answer

As the comments from @MonkeyZeus suggests, performance will improve by using the SQL count() function. Codeigniter provides this through the Query Builder function count_all_results($table = '', $reset = TRUE).

The function will take into account any restrictors you have put in place e.g. where, or_where, like, etc.

Change this

$query = clone $this->db;
$config['total_rows'] = $query->get('videos')->num_rows(); 

to this

//next line is not needed because the query will not be reset by the row count
//$query = clone $this->db;
$config['total_rows'] = $this->db->count_all_results('videos', FALSE); 

I’d be interested in knowing how execution time changes.