Why Vector Databases Are Critical for RAG Systems

A practical look at the retrieval layer of RAG — what a vector database actually does, why keyword search fails, and what it costs to get it wrong. A few weeks ago, a health-tech client sent me a screenshot that made me stop typing. His RAG system had answered a doctor's question about a medication interaction with a dosing suggestion that was wrong — not subtly wrong, dangerously wrong. The…