public function getTopWaitTimes($limit = self::TOP_X_LIMIT, $minDelay = self::TOP_X_MIN_DELAY)
    {
        $query = $this->pdo->prepare(<<<SQL
SELECT
  base,
  userAgent,
  delayUntil / 1000000 AS delayUntil,
  lastDelay / 1000000 AS lastDelay
FROM robotstxt__delay0
WHERE delayUntil > ((UNIX_TIMESTAMP(CURTIME(6)) + :minDelay) * 1000000)
ORDER BY delayUntil DESC
LIMIT :maxCount;
SQL
        );
        $query->bindValue('minDelay', $minDelay, \PDO::PARAM_INT);
        $query->bindValue('maxCount', $limit, \PDO::PARAM_INT);
        $query->execute();
        return $query->fetchAll(\PDO::FETCH_ASSOC);
    }