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News
Distributed Locks
1+ hour, 34+ min ago (110+ words) One-liner: A distributed lock ensures that only one node in a cluster can perform a critical operation at a time — preventing race conditions across services. In a single-server world, a mutex or semaphore handles concurrency. But in distributed systems: Classic…...
Day 8 - Relational Database 101 - PostgreSQL Internals
2+ hour, 13+ min ago (1576+ words) একবার একটু technological দিকে আসি, আপনি যখন Facebook বা LinkedIn-এ কাউকে message করেন তখন সেটা সরাসরি তার কাছে send হয়। Reason হচ্ছে আপনারা connected। এখানে আপনি directly message ত…...
The database connection pool was configured with 50 connections, so why did the 20th request time…
6+ hour, 11+ min ago (30+ words) The database connection pool was configured with 50 connections, so why did the 20th request time out? Understanding how parallel database queries inside a single HTTP request can exhaust your …...
Our users’ phones were the backup: rebuilding a lost database from app caches
6+ hour, 58+ min ago (223+ words) How expired cache entries on readers’ devices, server logs, and a year-old dump were merged back into MongoDB without …...
Vanilla PostgreSQL vs Amazon Aurora PostgreSQL
7+ hour, 33+ min ago (1187+ words) At the application level, Amazon Aurora PostgreSQL looks like PostgreSQL. You connect with PostgreSQL drivers, run SQL, use transactions, indexes, MVCC. Underneath, it is a different database architecture. One sentence explains most of the difference: Vanilla PostgreSQL couples the database engine…...
Your app went viral. Adding servers made it worse. Here's why.
12+ hour, 40+ min ago (94+ words) It's midnight, someone huge shares your app, 100,000 people show up — and the page dies. You add three servers. It gets worse. The rule that finally made this click for me: before you add capacity, find out where the request is…...
Why Timestamps Lie in Distributed Systems (and How Logical Clocks Fix It)
13+ hour, 13+ min ago (476+ words) There's a line of code in almost every service that stores replicated data: def resolve(incoming,... Tagged with distributedsystems, backend, systemdesign, database....
Decoding a UUID by hand: version, variant, and the embedded timestamp
15+ hour, 51+ min ago (404+ words) The reason was practical. IDs arriving from other systems come with no documentation. When you generate them yourself you know the scheme; when you receive them you are guessing. The spec makes this mechanically decidable, so I wrote the reader....
Valkey 9.1 vs Redis 8.4: The Fork Finally Grew Up
17+ hour, 27+ min ago (456+ words) Back in March 2024, when Redis changed its license, the advice most teams got was simple: wait and see. Valkey, the Linux Foundation fork, was brand new. It was essentially Redis 7.4 with a different governance badge, and nobody wanted to migrate…...
Day 16: Cosine Similarity and Semantic Search Basics
19+ hour, 31+ min ago (495+ words) Cosine similarity measures how closely two vectors point in the same direction, regardless of their length. Picture a vector as an arrow from the origin in space. Cosine similarity looks at the angle between two such arrows. If they point…...