Blog
Articles on backend architecture, API design, and database patterns — NestJS, PostgreSQL, and building reliable server-side systems.
100 articles
When a service should call another and wait, and when it should publish a message instead: availability arithmetic, latency, failure handling, consistency, and the 202 Accepted hybrid.
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Partitioning splits a table inside one database server, sharding spreads data across several servers. Postgres DDL, EXPLAIN output and a shard router.
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Latency vs throughput explained: what each measures, how Little's law links them, why batching and queues trade one for another, and how to optimise both.
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A Bloom filter is a bit array plus k hash functions that answers maybe or definitely not. See the m and k formulas, a measured error rate and real uses.
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How does service discovery work in microservices? Registry, heartbeat and TTL, client-side vs server-side, DNS in Docker Compose and Kubernetes, Consul.
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How leader election works in distributed systems: a Postgres lease with a fencing epoch, Redis and etcd alternatives, Kubernetes Lease objects and split-brain.
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Pub/sub vs message queue: competing consumers versus fan-out, delivery guarantees, ordering, replay, consumer groups, and a checklist for jobs, notifications and events.
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How the Raft consensus algorithm works: terms and roles, randomized leader election, log replication and the commit index, quorum arithmetic for 3, 5 and 7 nodes, safety, and where etcd and Consul use it.
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Backpressure is how a slow consumer tells a fast producer to slow down. Learn bounded queues, load shedding, Node.js drain and queue-depth autoscaling.
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What the bulkhead pattern is, how one slow dependency drains a shared pool, how to isolate with pools, semaphores, queues and containers, and how to size each one.
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How to retry failed requests safely: which errors to retry, the retry storm arithmetic, exponential backoff with jitter, Retry-After, retry budgets and idempotency keys, with a runnable TypeScript helper.
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ACID vs BASE with Postgres examples: what each ACID letter protects, why BASE is a pun and not a standard, and how to choose per feature.
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What database transaction isolation levels are and which to use. PostgreSQL READ COMMITTED, REPEATABLE READ and SERIALIZABLE, shown with real two-session output and a retry loop.
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How to design a distributed key-value store the Dynamo way: consistent hashing, N/W/R quorums, vector clocks, hinted handoff, Merkle trees, gossip and an LSM node.
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How to design a flash sale system that does not oversell stock: atomic decrements in Postgres and Redis Lua, TTL reservations, a waiting room, sharded counters and reconciliation.
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What eventual consistency guarantees, how replicas converge with LWW, version vectors and CRDTs, and which features can tolerate stale reads and which cannot.
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Two-phase commit vs saga for distributed transactions: how 2PC blocks and holds locks, what PostgreSQL PREPARE TRANSACTION offers, and when a saga fits better.
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How to design a payment system that never loses or double-charges money: a payment state machine, an append-only double-entry ledger in integer cents, idempotency keys, webhooks and daily reconciliation.
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How do you design a web crawler that scales? A worked design: URL frontier, robots.txt under RFC 9309, dedup, DNS caching, crawler traps and recrawl scheduling.
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How to design a distributed job scheduler that runs each job once: slot rows, Postgres SKIP LOCKED leases, advisory locks, catch-up, retries and idempotent handlers.
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How to generate unique IDs across many servers: auto-increment limits, UUIDv4 index damage, UUIDv7 under RFC 9562, Snowflake's 41/10/12 layout, clock rollback and block allocation.
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How do apps find nearby drivers or places? Geohash vs quadtree explained with TypeScript, PostGIS ST_DWithin, Redis GEOSEARCH and write-rate maths.
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How to design a real-time chat application like WhatsApp: WebSocket gateways, ack and ordering with per-conversation sequence numbers, offline delivery, presence and group fan-out.
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How to design a news feed: fan-out on write versus fan-out on read, the celebrity problem, Redis sorted set feeds, cursor pagination and ranking, with the arithmetic shown.
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