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⚙️ System Design for AI in Production
Core

Prompt and Semantic Caching

Caching is one of the cheapest, highest-impact LLM optimizations. Prefix (prompt) caching reuses the computed attention state for a shared prompt prefix (a long system prompt or document), cutting prefill cost and latency. Semantic caching serves a stored answer for a query that is similar (not identical) to a past one, by embedding the query and matching nearest neighbors. Applied-AI interviews probe it because repetitive traffic is everywhere, and caching turns expensive recomputation into near-free lookups, with a correctness caveat for semantic caching.

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