SQL vs NoSQL: How to Choose
SQL vs NoSQL explained: data models, consistency, scaling, query flexibility and when to use relational, document, key-value, wide-column or graph databases.
Topic
Databases
Choosing, scaling and understanding databases: SQL, NoSQL, sharding and storage engines.
Database Sharding Explained
What database sharding is, when you need it, how to choose a shard key, range vs hash vs directory sharding, and the operational pain points to plan for.
B-Trees vs LSM Trees: How Databases Store Data
How B-tree and LSM-tree storage engines work, why one favours reads and the other writes, write and read amplification, compaction and which databases use each.
Database Indexing Explained
How database indexes work: B-tree and other types, composite and covering indexes, why queries ignore indexes, the write cost and checking with EXPLAIN.
Database Replication: Leader-Follower, Multi-Leader, Leaderless
Database replication explained: leader-follower, multi-leader and leaderless designs, sync vs async, replication lag, failover, quorums and conflict resolution.
ACID and Transaction Isolation Levels
ACID and isolation levels explained: dirty reads, lost updates, write skew and phantoms, what each level prevents, database defaults and practical fixes.