public function updateMulti(array $hashes)
    {
        $startSql = "UPDATE " . $this->tableName;
        $this->storage->exec('BEGIN TRANSACTION');
        foreach ($hashes as $id => $hash) {
            $this->storage->exec($startSql . " SET hash='$hash' WHERE id='$id'");
        }
        $this->storage->exec('END TRANSACTION');
    }