Reranking

What it is

Reranking is a second-pass ranking of search results using a more sophisticated model. Initial retrieval might return 100 candidates quickly; a reranker then evaluates each candidate more carefully against the query to produce a better final ranking. It balances speed and quality.

Why it matters

Reranking improves RAG quality significantly. Initial embedding-based retrieval is fast but imperfect. Rerankers catch relevant documents that initial search ranked too low and demote false positives. For production RAG systems, reranking often provides noticeable quality improvements.