posts_orderby (ok)

add_filter('posts_orderby', 'orderby_pages_callback', 10, 2);
function orderby_pages_callback($orderby_statement, $wp_query) {
		global $wpdb;
    # Verify correct post type, or any other query variable
    if ($wp_query->get("post_type") === "post") {
        # In this trivial example add a reverse menu order sort
        return " {$wpdb->posts}.post_date DESC ";
    } else {
        # Use provided statement instead 
        return $orderby_statement;
    }
}