Getting Started With PgVector in .NET for Simple Vector Search

pgvector is a PostgreSQL extension that adds vector storage and similarity search without requiring a dedicated vector database. This walkthrough covers setting up pgvector in a .NET application using .NET Aspire for infrastructure provisioning, Ollama with the qwen3-embedding model for generating embeddings, and Dapper for database access. It includes creating the vector column, enabling the HNSW index for fast approximate nearest-neighbor search, generating and storing embeddings, and querying by cosine distance. The IEmbeddingGenerator abstraction from Microsoft.Extensions.AI keeps the embedding provider swappable.