How implement cache on Search query sql

Hi guys,


I need to be able to cache all kinds of searches with like.
I have it this way, according to the documentation, but according to the profiler, it doesn't save in cache and the query is still running.


SearchModel

PHP Code:

public function search($product)
    {
        $this->db->cache_on();
        $data = $this->db
            ->select('name, slug')
            ->from('products')
            ->like('name', $product)
            ->or_like('slug', $product)
            ->limit(5)
            ->get()
            ->result_array();
         $this->db->cache_off();

        return json_encode($data);
    } 


SearchController:

PHP Code:

public function index($product)
    {
        $product = urldecode($product);
        $product = preg_replace('/\s+/', '-', $product);
        $this->load->Model('api/search/SearchModel');

        echo $this->SearchModel->search($product);

        $this->output->enable_profiler(TRUE);
    } 


Directory application\cache is empty...