This looks really cool! I'm excited to see a production deployment of DiskANN.

According to the single-threaded QPS experiments, your DiskANN solution should clock in at about 4.5ms latency (1000ms/224QPS) whereas pgvector is about 5.8ms latency (1000ms/173QPS). How is that possible? My (very shallow) knowledge of DiskANN vs HNSW tells me that DiskANN should generally have higher latency than HNSW — DiskANN needs to touch the SSD while HNSW only touches RAM.

Also, compared to pgvector and HNSWPQ in faiss, how much less RAM does your DiskANN-based solution use?