带有压缩行格式的MySQL：错误代码：1709。索引列大小太大。最大列大小为767字节

Question

我正在尝试使用AWS Aurora MySQL 5.7数据库设置ownCloud，但我得到了：
Error Code: 1709. Index column size too large. The maximum column size is 767 bytes.

这是我的疑问：

CREATE DATABASE owncloud CHARACTER SET utf8mb4 COLLATE utf8mb4_bin;
CREATE TABLE owncloud.oc_mimetypes (
  `id` INT AUTO_INCREMENT NOT NULL,
  `mimetype` VARCHAR(255) DEFAULT '' NOT NULL,
  UNIQUE INDEX mimetype_id_index (`mimetype`),
  PRIMARY KEY (`id`)
) ROW_FORMAT=COMPRESSED;

如果我删除了ROW_FORMAT选项，它会正常工作。

这是我的服务器配置：

mysql> show variables like "%version%";
+-------------------------+------------------------------+
| Variable_name           | Value                        |
+-------------------------+------------------------------+
| aurora_version          | 2.03.1                       |
| innodb_version          | 5.7.12                       |
| protocol_version        | 10                           |
| slave_type_conversions  |                              |
| tls_version             | TLSv1,TLSv1.1,TLSv1.2        |
| version                 | 5.7.12                       |
| version_comment         | MySQL Community Server (GPL) |
| version_compile_machine | x86_64                       |
| version_compile_os      | Linux                        |
+-------------------------+------------------------------+

mysql> show global variables like 'innodb_lar%';
+---------------------+-------+
| Variable_name       | Value |
+---------------------+-------+
| innodb_large_prefix | ON    |
+---------------------+-------+

mysql> show global variables like 'innodb_file%';
+--------------------------+-----------+
| Variable_name            | Value     |
+--------------------------+-----------+
| innodb_file_format       | Barracuda |
| innodb_file_format_check | ON        |
| innodb_file_format_max   | Barracuda |
| innodb_file_per_table    | ON        |
+--------------------------+-----------+

有什么主意吗？