Learn how idempotency keys turn unreliable networks into predictable APIs, so retries, timeouts, and double-clicks never create a duplicate payment or order. Covers server-side implementation, concurrency handling, what to cache, and common pitfalls.
Share your comments or suggestions to improve our content.
The complete guide to the cache-aside pattern with Redis: jittered TTLs, correct invalidation, and the three defenses against cache stampedes (distributed lock, single-flight, and XFetch). Expanded with stale-while-revalidate, fail-open and circuit breakers, two-tier caching with RESP3 invalidation, delayed double delete and CDC, hot keys, eviction and memory management, observability with Prometheus, testing, choosing an engine (Redis, Valkey, Memcached), and a complete TypeScript implementation. With production-ready code in Python and TypeScript.
Learn to implement the circuit breaker pattern so a failing dependency never drags down your whole system: the three states (closed, open, half-open), sliding failure windows, limited probes to avoid thundering herds, robust fallbacks, and how to combine it with timeouts, retries, and bulkheads. Includes distributed state in Redis, observability with Prometheus, pytest testing, circuit breaking in Envoy/Istio, a full case study, and production-ready code in Python and TypeScript.
Learn to design indexes that genuinely speed up your queries: B-tree, composite, partial, and covering indexes. Includes how to read EXPLAIN ANALYZE, correct column ordering, the mistakes that silently disable an index, and what's new in PostgreSQL 18.