Top Vector Databases for AI Agents in 2026: Qdrant vs Pinecone vs Weaviate vs PgVector vs Milvus Persistent memory is the foundation that turns a stateless LLM into a continuously improving, autonomous agent. In 2026, selecting a vector database is no longer just about raw Approximate Nearest Neighbor (ANN) speed. For AI agents, the critical requirements have shifted to: Payload & Metadata Filtering : Can you filter by tenant_id , user_id , and timestamp during vector graph...