Databases
Storing, querying and protecting data at scale.
The Relational Model
The relational model is the mathematical foundation — based on set theory and first-order logic — that makes every SQL database provably correct and query-optimizable.
SQL in Depth
SQL is the declarative language that lets you say *what* data you want and trust the database engine to figure out *how* to retrieve it — mastering it means mastering set theory, relational algebra, and the art of composable queries.
Database Design & Normalization
Master the art of organizing data so it stays consistent, queryable, and free of the hidden redundancy bugs that corrupt real systems.
Storage & Indexing
From spinning-disk physics to B+ tree surgery — master how databases actually store, find, and serve billions of rows at hardware speed.
Query Processing & Optimization
Query optimization is the art of automatically turning a declarative SQL statement into the fastest possible execution plan — the engine's brain that separates toy databases from industrial ones.
Transactions & ACID
Transactions give databases a superpower: all-or-nothing bundles of operations that survive crashes and concurrent chaos — the bedrock of every financial, medical, and social system on earth.
Concurrency Control
Concurrency control is the art of letting many transactions run simultaneously while making the database behave as if they ran one at a time.
Recovery & Durability
ARIES and write-ahead logging: how databases survive crashes and guarantee that committed transactions are never lost, no matter what fails.
Distributed & NoSQL Databases
Distributed and NoSQL databases let you trade some guarantees for massive scale — understanding exactly what you give up, and when it is worth it, is the art.