CoreNN is an open-source vector database designed to efficiently handle 1 billion embeddings on a single machine, overcoming the limitations of traditional algorithms like HNSW. It utilizes inexpensive flash storage, allows for seamless scaling, and maintains speed and accuracy with features like local graph optimizations for updates. Built on the principles of DiskANN and FreshDiskANN, CoreNN aims to simplify the querying and updating process while minimizing memory usage and write amplification.