WC_Product_Data_Store_CPT::get_related_products PHP Method

    public function get_related_products($cats_array, $tags_array, $exclude_ids, $limit, $product_id)
    {
        global $wpdb;
        return $wpdb->get_col(implode(' ', apply_filters('woocommerce_product_related_posts_query', $this->get_related_products_query($cats_array, $tags_array, $exclude_ids, $limit + 10), $product_id)));
    }