Laravel 6.x - Cache 'pagination()' - laravel

Question

I'm using Laravel pagination (https://laravel.com/docs/6.x/pagination#paginating-eloquent-results)
like this:
// the Controller contains
$users = App\User::paginate(15);
Running this code, I noticed that are executed two queries:
To get the number of total items: select count(*) as aggregate from user
To get the first 15 items: select * from user limit 15 offset 0
I'd like to cache this queries, and the question is: from App\User::paginate(15) is there a way to get the sql(s) that will be executed? select count(*) as aggregate from user and select * from user limit 15 offset 0?
The code App\User::paginate(15) return a LengthAwarePaginator class; can I get the sql executed from this class?
The idea is to create my own method to cache this pagination request. Something like:
// the Model contains
public static function paginateWithQueryCache($itemPerPage) {
$query = self::query();
$cacheKeyString = $query->toSql();
$cacheKeyStringMD5 = md5($cacheKeyString);
return \Cache::remember($cacheKeyStringMD5, 60, function() use ($itemPerPage) {
return self::paginate($itemPerPage);
});
}
// the Controller will be update with
$users = App\User:: paginateWithQueryCache(15);
The problem here is that the $query->toSql() used as a cache key, is a simple query to the model (select * from user) instead of a pagination query (select * from user limit 15 offset 0); this is a problem switching to second page, page=2.
Thank you.

Answer 1

The query select count(*) as aggregate from user (that is very slow in my case with millions of records in a database table) is executed from Illuminate\Database\Query::getCountForPagination(), then to cache it I need to extend the class and implement the cache.
I changed the approach and I decided to cache all pagination output:
// Controller
public function paginateCache($model, $cacheExpireInSeconds = 120)
{
$cacheKeyString = request()->fullUrl();
$cacheKeyStringMD5 = md5($cacheKeyString);
/* Closure to get data */
$func_get_data = function() use ($model) {
return $model::paginate(1000);
};
/* Caching */
return \Cache::remember($cacheKeyStringMD5, $cacheExpireInSeconds, $func_get_data);
}
public function index()
{
return $this->paginateCache(User::class);
}