public function addURLs($urls)
  {
    PHPCrawlerBenchmark::start("adding_urls_to_sqlitecache");

    $this->PDO->exec("BEGIN EXCLUSIVE TRANSACTION;");

    $cnt = count($urls);
    for ($x=0; $x<$cnt; $x++)
    {
      if ($urls[$x] != null)
      {
        $this->addURL($urls[$x]);
      }

      // Commit after 1000 URLs (reduces memory-usage)
      if ($x%1000 == 0 && $x > 0)
      {
        $this->PDO->exec("COMMIT;");
        $this->PDO->exec("BEGIN EXCLUSIVE TRANSACTION;");
      }
    }

    $this->PDO->exec("COMMIT;");
    $this->PreparedInsertStatement->closeCursor();

    if ($this->db_analyzed == false)
    {
      $this->PDO->exec("ANALYZE;");
      $this->db_analyzed = true;
    }

    PHPCrawlerBenchmark::stop("adding_urls_to_sqlitecache");
  }