$row = pg_fetch_assoc($res);
        return $row["timestamp"];
    }
    // Adds the cached document referenced by $id to the provided pdf
    static function insert_cached_document(CPDF_Adapter $pdf, $id, $new_page = true)
    {
        $res = self::__query("SELECT font_name FROM page_fonts WHERE id='" . pg_escape_string($id) . "'");
        // Ensure that the fonts needed by the cached document are loaded into
        // the pdf
        while ($row = pg_fetch_assoc($res)) {
            $pdf->get_cpdf()->selectFont($row["font_name"]);
        }
        $res = self::__query("SELECT data FROM page_cache WHERE id='" . pg_escape_string($id) . "'");
        if ($new_page) {
            $pdf->new_page();
        }
        $first = true;
        while ($row = pg_fetch_assoc($res)) {
            if (!$first) {
                $pdf->new_page();
            } else {
                $first = false;
            }
            $page = $pdf->reopen_serialized_object($row["data"]);
            //$pdf->close_object();
            $pdf->add_object($page, "add");
        }
    }
}
Page_Cache::init();