maria-discuss team mailing list archive

[andrei.elkin@xxxxxxxxxx]

Hello there, Bapt.

> Hello,
>
> On Ubuntu 19.04, which uses packages mariadb-server 10.3.17 and
> mysql-server 5.7.27, I noticed that if I wanted to switch from MySQL to
> MariaDB, the database is corrupted and there is a complete data loss
> even if I switch back to MySQL.

 > I noticed that if I wanted to switch from MySQL to
 > MariaDB, the database is corrupted

The following text does not refer to any specific error at MySQL -> MariaDB
mirgration. While it's of interest on its own, it also can bring in few
details to what went wrong at the restoring attempt.


Cheers,

Andrei


> In the previous version of Ubuntu, switching from MySQL to MariaDB did
> not manage to import data automatically (unlike Debian) but at least it
> created a backup of the data in /var/lib/mysql-5.7/ folder which is not
> done anymore.
>
> Here is the error message I saw during install when trying to use the
> database corrupted by MariaDB and switching back to MySQL:
> "MySQL has been frozen to prevent damage to your system. Please see
> /etc/mysql/FROZEN for help."
>
> And in /var/log/mysql/error.log:
> "[ERROR] InnoDB: Unsupported redo log format. The redo log was created
> with MariaDB 10.3.17. Please follow the instructions at
> http://dev.mysql.com/doc/refman/5.7/en/upgrading-downgrading.html";
>
> I was able to reproduce the issue with a clean installation of Ubuntu
> 19.04 in VirtualBox.
>
> Do you know where the problem comes from and if it is possible to fix
> the binary data from /var/lib/mysql/ to make it work with either MySQL
> or MariaDB?
> It looks like MariaDB tried to convert the data ("[ERROR] InnoDB:
> Unsupported redo log format") but now it fails with both MySQL and MariaDB.
> Is it possible to revert the changes done by MariaDB to make the data
> work again with MySQL? (and then do a proper backup with mysqldump)
>
> Thanks.
>
> _______________________________________________
> Mailing list: https://launchpad.net/~maria-discuss
> Post to     : maria-discuss@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~maria-discuss
> More help   : https://help.launchpad.net/ListHelp