RDBMS · NoSQL · Beyond

Database Systems

Explore relational and non-relational databases side by side — when to use SQL vs document stores, how indexing works, and what interviewers expect at FAANG and startups.

Open the Databases roadmap Relational foundations first, then the NoSQL and specialised stores, as one connected roadmap. Explore →
Quick Compare

Pick the right database type

TypeBest forExamplesTrade-off
RelationalTransactions, reporting, joinsPostgreSQL, MySQLSchema rigidity
DocumentFlexible JSON documentsMongoDB, FirestoreJoin complexity
Key-valueCache, sessions, rate limitsRedis, DynamoDBLimited query patterns
GraphRelationships, recommendationsNeo4j, NeptuneNiche, ops overhead