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Database Requirements

L2J Mobius Chronicle 4 requires a MySQL or MariaDB database server.

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Supported Versions

  • MySQL: 5.7 or higher
  • MariaDB: 10.3 or higher (recommended)

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Database Structure

The server uses a single database for both login and game data:
  • Default database name: l2jmobiusc4
  • Contains both account and game world data

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Installing MySQL/MariaDB

# Install MariaDB (recommended)
sudo apt-get update
sudo apt-get install mariadb-server mariadb-client

# Start and enable service
sudo systemctl start mariadb
sudo systemctl enable mariadb

# Secure installation
sudo mysql_secure_installation

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Creating the Database

1

Connect to MySQL

mysql -u root -p
Enter your root password when prompted.
2

Create Database

CREATE DATABASE l2jmobiusc4 DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
The database name l2jmobiusc4 matches the default configuration in the server files.
3

Create Database User

-- Create user (replace 'your_password' with a strong password)
CREATE USER 'l2jmobius'@'localhost' IDENTIFIED BY 'your_password';

-- Grant privileges
GRANT ALL PRIVILEGES ON l2jmobiusc4.* TO 'l2jmobius'@'localhost';
FLUSH PRIVILEGES;

-- For remote access (optional, adjust IP as needed)
CREATE USER 'l2jmobius'@'%' IDENTIFIED BY 'your_password';
GRANT ALL PRIVILEGES ON l2jmobiusc4.* TO 'l2jmobius'@'%';
FLUSH PRIVILEGES;
Using root for the database connection is not recommended for production servers. Create a dedicated user with appropriate permissions.
4

Verify Database

SHOW DATABASES;
USE l2jmobiusc4;

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Installing Database Schema

L2J Mobius provides a DatabaseInstaller tool for easy schema installation.
1

Configure Database Connection

Before running the installer, configure the database connection in:db_installer/config/Database.ini
# Database driver (MySQL/MariaDB)
Driver = com.mysql.cj.jdbc.Driver

# Database connection URL
URL = jdbc:mysql://localhost/l2jmobiusc4?useUnicode=true&characterEncoding=utf-8&allowPublicKeyRetrieval=true&useSSL=false&connectTimeout=10000&interactiveClient=true&sessionVariables=wait_timeout=600,interactive_timeout=600&autoReconnect=true

# Database credentials
Login = l2jmobius
Password = your_password
Replace your_password with the password you created for the database user.
2

Run Database Installer

cd db_installer
chmod +x DatabaseInstaller.sh
./DatabaseInstaller.sh
The installer will:
  • Connect to your database
  • Display available SQL files
  • Allow you to install game and login tables
3

Install Tables

The DatabaseInstaller provides SQL scripts for:Login Server Tables (sql/login/):
  • accounts.sql - Player account data
  • account_data.sql - Extended account information
  • accounts_ipauth.sql - IP authentication
  • gameservers.sql - Registered game servers
Game Server Tables (sql/game/):
  • Over 100+ tables for game world data
  • Character data, items, clans, castles, etc.
  • Quest states, skills, inventory
  • Olympiad, sieges, and more
Select “Install” for both Login and Game schemas when prompted by the DatabaseInstaller.
4

Verify Installation

mysql -u l2jmobius -p l2jmobiusc4

-- Check installed tables
SHOW TABLES;

-- Verify key tables exist
SELECT COUNT(*) FROM accounts;
SELECT COUNT(*) FROM gameservers;
SELECT COUNT(*) FROM characters;

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Database Configuration Files

After schema installation, configure database connections for both servers: 
# ---------------------------------------------------------------------------
# Game Server Database Configuration
# ---------------------------------------------------------------------------

# JDBC Driver
Driver = com.mysql.cj.jdbc.Driver

# Database URL with connection parameters
URL = jdbc:mysql://localhost/l2jmobiusc4?useUnicode=true&characterEncoding=utf-8&allowPublicKeyRetrieval=true&useSSL=false&connectTimeout=10000&interactiveClient=true&sessionVariables=wait_timeout=600,interactive_timeout=600&autoReconnect=true

# Credentials (use dedicated user, not root)
Login = l2jmobius
Password = your_password

# Connection Pool Settings
# GameServer requires more connections for handling players
MaximumDatabaseConnections = 500

# Test connections before use (adds overhead)
TestDatabaseConnections = False

# ---------------------------------------------------------------------------
# Automatic Backup Settings
# ---------------------------------------------------------------------------

# Enable automatic backups on restart/shutdown
BackupDatabase = False

# MySQL bin folder path (Windows only)
MySqlBinLocation = C:/xampp/mysql/bin/

# Backup storage path
BackupPath = ../backup/

# Retention period in days (0 = unlimited)
BackupDays = 30
Both LoginServer and GameServer must use the same database (l2jmobiusc4) with identical credentials.

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Connection Pool Optimization

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GameServer Pool Settings

From game/config/Database.ini:20: 
# Default: 100, Recommended: 500 for high-population servers
MaximumDatabaseConnections = 500
The GameServer handles multiple simultaneous player connections and requires a larger connection pool.

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LoginServer Pool Settings

From login/config/Database.ini:20: 
# Default: 5 (sufficient for most setups)
MaximumDatabaseConnections = 5

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Database Backup Configuration

Enable automatic backups for production servers: 
# Enable automatic backups
BackupDatabase = True

# Windows: Specify MySQL bin location
MySqlBinLocation = C:/xampp/mysql/bin/

# Linux: Usually auto-detected, leave default
# MySqlBinLocation = /usr/bin/

# Backup storage path (relative to server directory)
BackupPath = ../backup/

# Automatically delete backups older than X days
BackupDays = 30
Backups are triggered when the server restarts or shuts down gracefully.

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Troubleshooting

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Connection Errors

Error: “Access denied for user” 
# Verify user permissions
mysql -u root -p

SHOW GRANTS FOR 'l2jmobius'@'localhost';
GRANT ALL PRIVILEGES ON l2jmobiusc4.* TO 'l2jmobius'@'localhost';
FLUSH PRIVILEGES;
Error: “Unknown database ‘l2jmobiusc4’” 
CREATE DATABASE l2jmobiusc4;
Error: “Too many connections” 
-- Check current connections
SHOW PROCESSLIST;

-- Increase max connections in MySQL config
SET GLOBAL max_connections = 1000;

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Performance Tuning

For high-population servers, optimize MySQL settings in /etc/mysql/my.cnf or my.ini: 
[mysqld]
max_connections = 1000
innodb_buffer_pool_size = 4G
innodb_log_file_size = 512M
innodb_flush_log_at_trx_commit = 2
query_cache_size = 0
query_cache_type = 0
Restart MySQL after configuration changes:
sudo systemctl restart mariadb

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Next Steps

With the database configured:
  1. Configure the LoginServer
  2. Configure the GameServer
  3. Review server configuration files

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