When the autonomous customer‑support bot at Acme Corp crashed after 2 hours, the logs showed a 92 % drop in relevance caused by a pure‑vector store that couldn't resolve relational queries.
Why Pure Vector Stores Fail on Relational Reasoning
The 0‑shot similarity trap
Vector stores excel at nearest‑neighbor look‑ups, but they treat every piece of text as a point in space. The moment a query needs to reason about how two entities relate, similarity alone falls apart. In our own experiments, a simple “upgrade my plan” request returned a vector match for the word upgrade but ignored that the user was on a Basic tier, so the bot suggested a Premium plan that the user could not legally purchase.
Case study: FAQ mismatch rates
