Pinecone vs Weaviate vs Milvus vs Qdrant: Which Vector DB in 2026?

I have helped a number of teams pick a vector database in the last year. The conversation always starts the same way: four logos, one Slack message, one question — which one? The honest answer is that all four are good. The useful answer is that each one is built for a different set of constraints. Getting this decision wrong does not break your application on day one. It shows up six months later when your bill is three times your compute budget, or your filtered search recall starts degrading…