线上出现报错 Memory allocation error:

PDOException:SOLSTATE[HY001]: Memory allocation error: 1038 0ut of sort memory,
consider increasing server sort buffer size in phar:/.../vendor/illuminate/database/connection.php

$paginator = $model->orderByDesc("created_at")->orderBy($orderBy, $asc)->paginate($page_size);
$total = $paginator->total();
$items = $paginator->items();

[mysqld] 
sort_buffer_size = 256000000