Filtered Vector Search: Where Every Benchmark Quietly Lies to You

Let me show you a magic trick every vector database benchmark performs. Step one: run a query with no filter. Just "find me the nearest neighbors to this vector." Step two: report the gorgeous QPS numbers and the 95% recall. Step three: take a bow while everyone claps. Here is the query you actually run in production: nearest neighbors to WHERE tenant_id = 'acme' AND status = 'active' AND created_at > '2026-01-01' And here is where the applause stops. Latency triples. Recall quietly falls off a…