RAG Series (13): Query Optimization — Asking Better Questions

The Same Question, Completely Different Results Vector retrieval has a fragility that's easy to overlook: rephrase the same question, and the results can change dramatically. "How does the BGE model perform on Chinese text?" and "Which embedding is recommended for Chinese?" are semantically near-identical — but their embedding vectors sit at different positions in high-dimensional space, often returning different document sets entirely. This is a structural property of Bi-Encoders: query and doc