private function getStringTypePrefix($length = null)
    {
        if ($length === null) {
            return 'LONG';
        }

        if (!is_int($length) || ($length <= 0)) {
            throw PlatformException::invalidStringTypePrefixLength();
        }

        $prefixLimits = array(
            'TINY'   => 255,
            ''       => 65535,
            'MEDIUM' => 16777215,
        );

        $stringTypePrefix = 'LONG';
        foreach ($prefixLimits as $prefix => $limit) {
            if ($length <= $limit) {
                $stringTypePrefix = $prefix;

                break;
            }
        }

        return $stringTypePrefix;
    }