What are the differences between a relational database and a file system?

Relational databases and file systems are both methods for storing data, but they serve different purposes and operate in distinct ways. A relational database (RDBMS) organizes data into structured tables with predefined schemas, using rows and columns to represent records and their attributes. Relationships between tables are established through keys, enabling complex queries and data integrity. In contrast, a file system manages unstructured or semi-structured data as files and directories, typically stored in a hierarchical structure. While file systems are built into operating systems (e.g., NTFS, ext4), relational databases like MySQL or PostgreSQL are specialized software systems designed for efficient data management.

The key difference lies in how they handle data organization and access. Relational databases enforce strict schemas, ensuring consistency and validation (e.g., requiring a “user_id” column to be an integer). They support SQL for querying, allowing joins across tables and aggregations (e.g., finding orders from customers in a specific region). File systems lack such structure: a text file or image stored in a folder has no inherent schema, making it harder to enforce rules or query metadata (e.g., filtering files by creation date requires manual parsing). Databases also provide transactional guarantees (ACID properties), ensuring operations like bank transfers either fully succeed or roll back. File systems, while capable of basic locking, don’t natively support transactions, risking data corruption if a write operation fails midway.

Use cases further differentiate the two. Relational databases excel for applications requiring complex relationships, such as e-commerce platforms (e.g., linking users, orders, and products). They scale vertically and support concurrency (e.g., handling simultaneous user logins). File systems are better for storing large, unstructured data like documents, videos, or logs, where hierarchical organization suffices. For example, a photo-sharing app might use a file system to store images but rely on a database to track user metadata. While databases offer robustness, they require more setup and maintenance (e.g., schema migrations). File systems are simpler but lack advanced querying and consistency features, making them unsuitable for transactional or relational data needs.