How safe is it to enable mysql 4-byte support

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1

Hi everyone,

Since quite some years now I have a nextcloud instyance helping me getting away from the GAFAMs. This means that my database was also setup quite some years ago.

Now, I would like to enable mysql 4-byte support on my database.
the nextcloud version is 15 and mysql 5.5.62 on a debian 8.

If I follow the docs I should perform these steps:

SET GLOBAL innodb_file_format=Barracuda;

Then change my mysql conf to

[mysqld]
innodb_large_prefix=true
innodb_file_format=barracuda
innodb_file_per_table=1

Restart the mysql server

Update my nextcloud database

ALTER DATABASE nextcloud CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

And finish with these:

sudo -u www-data php occ config:system:set mysql.utf8mb4 --type boolean --value="true"
sudo -u www-data php occ maintenance:repair

After these steps, and some magics and the mysql side, everything should have been converted without problems ???

I am only wondering if changing the innodb settings is safe on a server that also has other batabases in it ?

I am not a MySQL expert at all but changing the innodb settings that easily looks like magics to me so that’s why I am wondering!

Any help/thoughts are welcome!

2

hello,

i ve done it on stretch without troubles.
The barracuda is applied to new db or tables. or apply with replication or recreation.
old table stayed in antilope.

Remember debian 8 EOL is july 2020…

maybe upgrading to stretch or buster is a smarter move ?

3

I think this is supposed to be a safe procedure if done how Nextcloud docs say to do it, but if safe is what you want, then I would either put it in maintenance mode and backup/snapshot or copy your setup to a test environment to see if it’s going to break anything.

4

My debian is indeed getting old, upgrading will happen soon (stretch, then, buster).

Alright, so changing the charset seems safe, but i do not get why the change is file format is required since it will only affect new db/tables. Or am I not knowledgeable enough to understand what’s going on on the MySQL side (that is definitely an option)

I also read that the file format would not be barracuda, unless the specific requirement like the row format require the barracuda format.

So now, I am wondering how the file format in related to the charset…