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Showing posts from November, 2025

How Netflix Ranks Your Shows: The Data Structures Behind

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Why Netflix Knows What You’ll Watch Next Every time you open Netflix, your homepage feels magically tailored for you. Titles appear in an ideal order — a mix of what you’ve watched, what’s trending, and what you’re likely to enjoy next. Behind this “effortless personalization” lies a powerful combination of  data science and data structures , primarily  heaps  and  priority queues . Netflix operates across regions with over 10,000 titles and millions of simultaneous users. Determining your top 10 shows in milliseconds requires not just AI but also  optimized data structure logic . This article breaks down that secret — how  heaps and priority queues  make ranking, caching, and streaming lightning-fast, both for Netflix and other global tech systems. The Data Structures Powering Netflix Heaps: The Unsung Heroes of Ranking A  heap  is a  complete binary tree  that maintains an order property between parent and child nodes. Max Heap: ...

Your React.memo is Lying to You. Here’s Why useCallback is the Answer.

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2030 Your React is Lying to You. Here’s Why useCallback is the Answer.   You have a component that’s re-rendering way too often. You identify an expensive child component, wrap it in   React.memo   .But then you open the profiler, and it’s still re-rendering every single time the parent does. It’s not broken, but it’s being tripped up by one of JavaScript’s fundamental truths:  functions are objects . And in the world of React, that little detail can cost you dearly in performance. Today, we’ll unravel this mystery and show how the  useCallback  hook is the key to making your optimizations actually work. When  React.memo  Fails We have a  ParentComponent  that holds some state, and it passes a function down to a  ChildComponent . To prevent the child from re-rendering unnecessarily, we've wrapped it in  React.memo . As a  quick refresher ,  React.memo  is a higher-order component that tells React,  "Don't re...