Install MySQL on Debian 12

Step 1 – Install MySQL

apt update && apt upgrade -y
apt install -y mysql-server
systemctl enable --now mysql

Step 2 – Secure the installation

mysql_secure_installation

Follow the prompts to set the root password, remove anonymous users, disallow remote root login, and remove the test database.

Step 3 – Connect

mysql -u root -p

Step 4 – Create a database and user

CREATE DATABASE appdb CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
CREATE USER 'appuser'@'localhost' IDENTIFIED BY 'StrongPass123!';
GRANT ALL PRIVILEGES ON appdb.* TO 'appuser'@'localhost';
FLUSH PRIVILEGES;
EXIT;

Step 5 – Configuration file

Main config: /etc/mysql/mysql.conf.d/mysqld.cnf

Important defaults to tune:

[mysqld]
# InnoDB buffer pool – set to 70–80% of available RAM
innodb_buffer_pool_size = 1G

# Slow query logging
slow_query_log = 1
slow_query_log_file = /var/log/mysql/slow.log
long_query_time = 1

# Binary logging (required for replication)
log_bin = /var/log/mysql/mysql-bin
binlog_expire_logs_seconds = 604800