Pradeep Kumar Saini | Tech | System Design | Career | AI on Instagram: "When a celebrity like Virat Kohli posts, Instagram doesn’t sort every single comment in real time. That would crash the system. Instead, it uses event streaming, smart ranking algorithms, caching (Redis), and background processing to precompute only the top 50–100 comments. This is a real-world system design problem solved at billion-user scale, using techniques every backend engineer should know. If you’re preparing for sys