https://preview.vvivid.dev/tags/system-design/Recent content in System-Design on Ou David | Systems EngineerHugo -- gohugo.ioen-usWed, 21 Jan 2026 08:48:01 +0100https://preview.vvivid.dev/posts/handling_fractional_cents_integration/Wed, 21 Jan 2026 08:48:01 +0100https://preview.vvivid.dev/posts/handling_fractional_cents_integration/<p>I&rsquo;m back with another story about a &ldquo;silent error&rdquo; in our systems. In my <a href="https://preview.vvivid.dev/posts/the_silent_timezone_mismatch_go_vs_mongodb">previous post</a>, I talked about how implicit timezone conversions can bite you. Today, let&rsquo;s talk about a different type of error: a design flaw when dealing with money.</p> <h3 id="the-real-problem">The Real Problem</h3> <p>We are building a Central Reservation System (CRS) for a tourist park. One of our golden rules when dealing with money is simple: <strong>always use integers</strong>. We convert everything to cents before pushing it to our cash-register API.</p>