Llm Gateway Cost And Caching easy
Your semantic cache uses a loose similarity threshold. Users asking "How do I cancel my order?" sometimes get the cached answer for "How do I cancel my subscription?". What should you change?
- A Raise the similarity threshold so only very close queries count as cache hits.
- B Lower the similarity threshold so the cache considers more candidate matches.
- C Increase the cache TTL so the stored answers stay valid for a longer period.
- D Use a larger embedding dimension but keep the same similarity match threshold.
Answer: A. Raise the similarity threshold so only very close queries count as cache hits.
The threshold trades **hit rate against wrong answers**: a loose threshold matches queries that look alike but mean different things. Raising it reduces false hits at the cost of fewer cache hits. Lowering it makes the problem worse; a looser threshold is only appropriate when near-miss answers are harmless, such as generic greetings.
One system design question a day, with spaced repetition so the ones you miss come back.
Get the appRelated questions
- Your primary LLM provider is fully down for an hour, and no tested fallback exists for your agent feature. The product also has an FAQ answer feature backed by a semantic cache. What is the best degradation mode?
- Your gateway applies one 5-second timeout to all LLM calls. Classification calls work fine, but long streamed answers are frequently cut off. What is the best fix?
- A multi-tenant B2B support assistant answers questions using each customer's private knowledge base. To raise the semantic cache hit rate from 22% to 35%, an engineer proposes one shared cache across all tenants. What is the main problem?
- During a provider brownout returning 429 and 503 errors, the client SDK retries 3 times and the gateway also retries 3 times, both immediately. Provider load spikes, and the bill grows from partially streamed responses. What should you change?
- Finance asks for LLM spend broken down by tenant and by product feature. Today the gateway only sees the total on the provider's monthly invoice. What should you do?
- A retail assistant uses a semantic cache. Weeks after a store changed its holiday hours, users still receive the old hours from cached answers. What is the right fix?