Codeigniter reused active record query

SELECT `d`.`district_id`,
       `d`.`enable`,
       `d`.`district_code`,
       `d`.`district_name`,
       `p`.`province_name`
FROM   `district` AS `d`
       LEFT JOIN `province` AS `p`
              ON `d`.`province_id` = `p`.`province_id`

SELECT `d`.`district_id`,
       `d`.`enable`,
       `d`.`district_code`,
       `d`.`district_name`,
       `p`.`province_name`
FROM   `district` AS `d`
       LEFT JOIN `province` AS `p`
              ON `d`.`province_id` = `p`.`province_id`
LIMIT  0, 10

SELECT COUNT(district_id) AS recordsTotal
FROM   `district` AS `d`
       LEFT JOIN `province` AS `p`
              ON `d`.`province_id` = `p`.`province_id`

<?php
 
class DatabasecachingModel extends CI_Model
{
 
    public function __construct()
    {
        // Call the CI_Model constructor
        parent::__construct();
 
        $this->db = $this->load->database('db', true);
    }
 
    public function getPagination()
    {
        $post = $this->input->post();
 
        // Turn caching on
        $this->db->start_cache();
 
        $this->db->from('district AS d');
        $this->db->join('province AS p', 'd.PROVINCE_ID = p.PROVINCE_ID', 'left');
 
        if (isset($post['DISTRICT_ID'])) {
            $this->db->where('DISTRICT_ID', $post['DISTRICT_ID']);
        }
 
        if (isset($post['PROVINCE_ID'])) {
            $this->db->where('PROVINCE_ID', $post['PROVINCE_ID']);
        }
 
        $this->db->stop_cache();
 
        $this->db->select('COUNT(DISTRICT_ID) AS recordsTotal');
        $recordsTotal = $this->db->get()->row()->recordsTotal;
 
        echo '<br><br> query string for count = ' . $this->db->last_query();
        echo '<br> records total = ' . $recordsTotal;
 
        $this->db->select('d.DISTRICT_ID, d.enable, d.DISTRICT_CODE, d.DISTRICT_NAME, p.province_NAME');
        $this->db->limit(10, 0);
        $results = $this->db->get()->result_array();
 
        echo '<br><br> query string for results = ' . $this->db->last_query();
        echo '<pre>', print_r($results, true), '<pre>';
 
    }
 
}