A practical guide to implementing vector similarity search in PostgreSQL using the pgvector extension. Covers installing pgvector, creating tables with vector columns, inserting embeddings, and querying with SQL distance operators. Explains the difference between L2 and cosine distance metrics, when to use each, and how to create HNSW or IVFFlat indexes for performance at scale. Also shows how to combine vector similarity queries with standard SQL WHERE filters for filtered semantic search.
Table of contents
IntroductionWhat Is a Vector Embedding?What Is pgvector?Installing pgvectorCreating a Table with a Vector ColumnInserting Sample DataRunning a QueryChoosing a Distance MetricAdding an Index for PerformancePutting It Together: Filtered Similarity SearchSummary & Next StepsSort: