Post by Prateek Jalgaonkar

Ever noticed this on ecommerce site? You check a product. It says: “Only 2 left in stock.” You refresh… Still 2 left. Come back later… Still 2. Is the site just… lying? Not exactly. That number is often not real-time inventory. Because updating stock instantly for millions of users is expensive and slow. So systems often: • Cache inventory • Update it in intervals • Or even show “safe estimates” Why? Because: Perfect accuracy at scale = slower experience So instead, they choose: Fast + close enough Which means: That “2 left” might not be exact… it’s just good enough to act on #SystemDesign #Everydaylife #DataEngineering