Overview
A database management system (DBMS) exists to store data reliably, query it efficiently, and let
Relational Model & SQL
The relational model, introduced by Edgar F. Codd in 1970, represents all data as relations
Indexing & Storage Engines
Without an index, finding a row that matches a condition means reading every row in the table — a
Transactions & ACID
A transaction groups multiple reads/writes into a single logical unit of work. ACID —
NoSQL & CAP Theorem
Once a database is replicated across multiple machines to survive failures and scale reads, it