Database Internals
What happens inside a database engine — B-tree indexes, heap vs index scans, ACID guarantees, write-ahead logging, and MVCC concurrency.
Database Internals2 min read
SQL looks declarative: you say what you want, not how to get it. Behind the scenes the database engine is doing a remarkable amount of work — choosing access paths, maintaining indexes, writing to disk in a way that survives crashes, and serving concurrent queries without corrupting each other's data.
This track covers three lessons:
- How indexes work — B-tree structure, heap scans vs index scans, and why
SELECT *can hurt performance - ACID and write-ahead logging — the four durability guarantees every SQL database makes, and how WAL implements crash recovery
- MVCC and concurrency — how databases serve concurrent readers and writers without locking, and the cost of keeping multiple row versions
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