Databases & Storage

Data is the lifeblood of modern applications. A professional engineer must not only know how to write code, but also how to persist, query, and manage state efficiently at scale. Selecting the right database is one of the most critical architectural decisions you will make.

In this section, we cover everything from the internal mechanics of relational systems to advanced SQL query optimization, NoSQL architectures, and specialized data stores.

What's Inside?

• Database Paradigms: OLTP vs. OLAP and the CAP Theorem.
• Relational Databases: RDBMS architecture, normalization, and ACID guarantees.
• SQL Fundamentals: Core statements, joins, aggregations, and window functions.
• SQL Query Optimization: EXPLAIN plans, index strategies, and performance pitfalls.
• Document & Key-Value Stores: Schema flexibility and horizontal scaling.
• Wide-Column & Graph Databases: Massive throughput and complex relationship modeling.
• In-Memory & Caching: Ultrafast access and eviction policies.
• Search & Time-Series: Specialized stores for logs, metrics, and text search.
• Choosing the Right Database: A pragmatic guide to evaluating trade-offs.

"Your application code is ephemeral. Your data is forever."