Glossary term
What is Bloom filter? Meaning for developers
In System Design
A tiny structure that says "definitely not here" or "maybe here". Example: Skips reading files that can't contain a key.
Learn it properly · System DesignLesson 16: Caching Part 2: Strategies, Eviction and InvalidationAdding a cache is easy; keeping it correct is hard. The six read/write strategies, why you delete rather than update on write, eviction policies you can try by hand, invalidation per data type, and the five ways caches cause outages.In System Design Case Studies 2
A small structure that says 'definitely not seen' or 'probably seen'. It never forgets an item but can give false positives.
Learn it properly · System Design Case Studies 2Lesson 0: Design a Web CrawlerThe URL frontier, politeness, Bloom-filter dedup and trap defence, with a crawler simulation you can run.