CockroachDB

Crate is an open-source distributed SQL database with support for vector data types and vector search, suitable for AI-driven applications.

Built-in vector search capability in TiDB, a MySQL-compatible database, enabling seamless storage and search for vectors using SQL with HNSW indexes. Eliminates the need for separate vector databases by combining operational and vector data.

Distributed NoSQL database with vector search capabilities via Storage-Attached Indexes (SAI) in Cassandra 5.0+. Uses Lucene HNSW for approximate nearest neighbor search. This is an OSS database under Apache 2.0 license.

An in-memory, open-source, and free analytical database that speaks SQL, heavily based on vectorization. It can store and process vector embeddings using Array and List data types to enable vector search, bridging the gap between data engineering and AI workflows with fast response times.

Milvus is a high-performance, open-source vector database designed for managing massive-scale embedding vectors in AI applications. It excels in similarity search using advanced indexing like HNSW and IVF, supports distributed deployment for billions of vectors, GPU acceleration, and hybrid search combining vector and scalar filters. Key use cases include RAG pipelines, recommendation engines, and image/video retrieval; it outperforms single-node DBs like Faiss in scalability but requires more setup compared to managed options like Pinecone.

PostgreSQL extension providing 230+ SQL functions as pgvector replacement, enabling vector search, graph queries, and AI features directly in relational databases.