Rag And Retrieval medium
To 'never miss anything,' a team raised the number of chunks sent to the generator from 5 to 40. Answer accuracy dropped slightly, while latency and token cost rose about 6x. What best explains the accuracy drop?
- A Extra low-relevance chunks add noise that distracts the model and dilutes attention, while every chunk costs tokens.
- B Reranker scores are less reliable past rank 10, so the best chunks end up ordered lower in the context.
- C Retrieval latency rose, so more requests hit the generator timeout and returned partial answers.
- D Forty chunks pushed the question out of the model's recent-token window, so it attended only to the last chunks.
Answer: A. Extra low-relevance chunks add noise that distracts the model and dilutes attention, while every chunk costs tokens.
A higher k raises recall, but past a point precision collapses. Low-relevance chunks then **distract the generator** and consume tokens. A better pattern is to retrieve wide, rerank, and send a small top set. Reranker order and timeouts are tempting causes, but the drop appears with or without a reranker and the requests complete. Models read the whole prompt, so there is no recent-token window. A large final k is justified for aggregation-style questions that need evidence from many documents.
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