How to permanently increase innodb_buffer_pool_size on Ubuntu
Here's what worked for me (ubuntu 19, mysql 8):
sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf
add in this at the bottom of the file
innodb_buffer_pool_size = 8G
save and exit. restart MySQL.
sudo systemctl restart mysql
The problem is, there are no such settings in my /etc/mysql/my.conf.
So add the lines needed to the [mysqld] section of the config file. The default my.cnf file only contains a tiny fraction of the configuration values that are available.