What's wrong with dumping MySql database?

Question

MySQL

Good day everyone.
I suddenly ran into a problem.
Site on wordpress.
Worth the Disqus comments plugin.
When installing the plugin in the database, the wp_commentmeta table was created.
Everything works.
I do base dump through the mysqldump console - the dump becomes.
But I can’t load it back through the console, I get an error

ERROR 1071 (42000) at line 53: Specified key was too long; max key length is 1000 bytes

We look at what is there in the dump on line 53.
A table is created:

DROP TABLE IF EXISTS wp_commentmeta;
/*!40101 SET @saved_cs_client = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE wp_commentmeta (
meta_id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
comment_id bigint(20) unsigned NOT NULL DEFAULT ‘0’,
meta_key varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
meta_value longtext COLLATE utf8mb4_unicode_ci,
PRIMARY KEY (meta_id),
KEY comment_id (comment_id),
KEY meta_key (meta_key(191)),
KEY disqus_dupecheck (meta_key,meta_value(11))
) ENGINE=MyISAM AUTO_INCREMENT=19 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

Line 53 is adding a key by two fields
KEY disqus_dupecheck (meta_key,meta_value(11))
. There are about 400 entries in the wp_commentmeta table, but the problem occurs even when there are 2 entries (I tried it on an old backup).
What does she not like and how was this table originally created with such a key?
Thank you!
PS: If you delete this line with handles, then the dump is filled normally, but the soul is somehow restless.

Answer 1

Very similar to this https://bugs.mysql.com/bug.php?id=4541
1. try migrating to innodb
2. try migrating to innodb mysql > 5.5.14 with https://dev.mysql.com/ doc/refman/5.5/en/innodb-par...