What is pgvector and why is it popular?

pgvector is an open-source PostgreSQL extension that adds a vector data type and similarity search functions, turning any Postgres database into a vector database. It has exploded in popularity because it lets teams add vector search to existing Postgres deployments without operating a separate database, inheriting Postgres's mature tooling, replication, backups, transactions, and security. pgvector supports HNSW and IVFFlat indexes, cosine, Euclidean, and inner product distances, and integrates with major hosted Postgres services like Supabase, Neon, and AWS RDS.