protected function eachPageUncache($selector, callable $callback)
	{
		$num = 0;
		$id = 0;
		while (true) {
			$p = $this->pages->get("{$selector}, id>$id");
			if(!$id = $p->id) break;
			$callback($p);
			$this->pages->uncacheAll($p);
			$num++;
		}
		return $num;
	}