Do we need a vector database or can we use pgvector?

pgvector is fine up to a few million vectors and moderate QPS — no operational overhead if you already run Postgres. Dedicated vector DBs (Pinecone, Weaviate, Qdrant, Milvus) start winning at higher vector counts, higher QPS, or when you need advanced features (hybrid search, streaming updates, per-tenant isolation at scale). Do not add a new system prematurely.