Databases
Database internals, indexing, transactions, and SQL/NoSQL
3 subjects · browse with filters
Database Indexing
Learn how B-tree and hash indexes work internally, how the query planner uses them, when to create composite and covering indexes, and how to diagnose slow queries using EXPLAIN ANALYZE.
SQL vs NoSQL & Data Modeling for Scale
Compare relational databases with key-value, document, wide-column, graph, search and time-series stores, learn access-pattern-driven modelling for DynamoDB and Cassandra, and use a decision matrix to justify database choices in interviews.
Database Replication & Sharding
Learn how single-leader, multi-leader and leaderless replication work, how quorums and failover behave, and how to shard a database by range, hash or directory — with shard-key selection, rebalancing, cross-shard queries and a worked 500M-user example.