What is a vector database, and which should an AI startup pick in 2026?

May 14, 2026 · AI

A practical 2026 guide to vector databases: what they are, when you need one, and how to choose between Postgres pgvector, Pinecone, Weaviate, Milvus, and more.

A vector database stores embeddings (numeric vectors) and lets you retrieve the most similar items fast for RAG, semantic search, recommendations, and agent memory. In 2026, most early AI startups should start with Postgres + pgvector if they’re <10M vectors and want operational simplicity; switch to a dedicated vector DB (Pinecone, Weaviate, Milvus, etc.) when you need higher recall/latency guarantees, horizontal scale, or richer filtering. Choose based on your workload (RAG vs. search), scale (vectors + QPS), filters, multi-tenancy, and how much infra you want to own.

Read the full article on Founders Bay.