Redmine

h1. HowTo convert a mysql database from utf8 to utf8mb4

First things you have to do is like an upgrade

h2. Step 1 - Check requirements

The first step to upgrading Redmine is to check that you meet the [[RedmineInstall#Requirements|requirements]] for the version you're about to use or install.

h2. Step 2 - Backup

It is recommended that you backup your database and file uploads. Most upgrades are safe but it never hurts to have a backup just in case.

To understand how to back up your Redmine, please read [[RedmineBackupRestore|Backing up and restoring Redmine]].

h2. Step 3 - Convert database and tables

When using a database with a current mySQL version, the conversion is already done with a single command line

<pre>

<code class="sql">

ALTER DATABASE redmine DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci

</code>

</pre>

More information about this topic, including how to convert the tables can be found:

* https://docs.nextcloud.com/server/20/admin_manual/configuration_database/mysql_4byte_support.html

* https://percona.community/blog/2018/06/12/character-sets-migrating-utf8mb4-pt_online_schema_change/

If you use an assistant such as _phpMyAdmin_, you can simply select the database there and select the item _Collation_ under the _Operations_ tab.

The conversion of the character set is now complete.

h2. Step 4 - Redmine configuration

Change in the file config/database.yml in the Redmine folder:

<pre>encoding: utf8mb4</pre>