AnhDH.

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New here? This is the curated path through my writing — the posts I'd hand someone who wants the most signal, fastest.

Distributed systems

  1. 1Message BrokerHave you ever wondered what keeps payment services, social networks, and delivery apps running smoothly every single day? The secret lies in the Messa…
  2. 2Distributed Locks and How to Implement Them with RedisIn distributed systems, ensuring data consistency and preventing race conditions is a major challenge, especially when many processes or services acce…

Databases

  1. 1COUNT(*) vs COUNT(1): Which One Performs Best?When counting rows in a table, we reach for the count function out of habit. But the count function accepts several kinds of arguments, such as count(…
  2. 2What Happens When MySQL Executes a SELECT Query?SELECT is usually the very first SQL statement anyone learns, yet few stop to ask what actually happens inside MySQL when that statement runs. This po…

Operations & tooling

  1. 1CronJob & Cron ExpressionsCronJob is an essential tool that lets developers automate tasks on a recurring schedule. To configure a CronJob correctly, however, you need a solid…

Backend

  1. 1Top 10 Java Core Interview QuestionsFoundational knowledge is something interviewers always check, whether you're a fresher or a senior engineer. This post rounds up the 10 most common J…