Database Servers on Linux

1. Introduction

Database servers are essential components of many applications, allowing for the storage, retrieval, and management of data. This lesson focuses on configuring and managing popular database servers on Linux, including MySQL, PostgreSQL, and MongoDB.

2. Key Concepts

2.1 What is a Database Server?

A database server is a server that runs a database management system (DBMS) and provides database services to other computer programs or computers, as defined by the client-server model.

2.2 Types of Database Servers

Relational Database Management Systems (RDBMS) - e.g., MySQL, PostgreSQL.
NoSQL Databases - e.g., MongoDB, Cassandra.

3. Installation

3.1 Installing MySQL

To install MySQL on a Linux server, follow these steps:

sudo apt update
sudo apt install mysql-server

After installation, secure the installation:

sudo mysql_secure_installation

3.2 Installing PostgreSQL

For PostgreSQL installation, use:

sudo apt install postgresql postgresql-contrib

3.3 Installing MongoDB

To install MongoDB, use the following commands:

sudo apt install -y mongodb

4. Configuration

4.1 Configuring MySQL

To configure MySQL, edit the configuration file:

sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf

Change settings such as:

Port number
Bind-address
Max connections

4.2 Configuring PostgreSQL

PostgreSQL configurations can be found in:

sudo nano /etc/postgresql/12/main/postgresql.conf

Common changes include:

Listen addresses
Port configuration

5. Best Practices

5.1 Security

Always secure your database server by:

Setting strong passwords.
Using firewalls to restrict access.
Regularly updating your database software.

5.2 Backup and Recovery

Implement regular backups to prevent data loss:

mysqldump -u root -p database_name > backup.sql

6. FAQ

What is the difference between SQL and NoSQL?

SQL databases are relational and structured, whereas NoSQL databases are non-relational and can handle unstructured data.

How do I check if my database server is running?

For MySQL, use: sudo systemctl status mysql. For PostgreSQL, use: sudo systemctl status postgresql.

7. Workflow Diagram


graph TD;
    A[Install Database] --> B[Configure Database];
    B --> C[Secure Database];
    C --> D[Backup Database];