At the <100k scale I just full compute / inner product directly, and I don’t mess with vector stores or added complexity. No ANN algo needed — they’ll all be slower than actual exact kNN re ranking. (10k7684 =30MB, a scan over it and a sort is on the ~100us or faster). frankly, I’ve even sent at the 5k scale to client and done that client side in JS.

Often, I find i use an ANN algo / index to get me my nearest 10k then I do final re ranking with more expensive algorithms/compute in that reduced space.

The original HNSW paper was testing/benchmarking at the 5M-15M scales. That’s where it shines compared to alternatives.

When pushing to the 1B scale (I have an instance at 200M) the memory consumption does become a frustration (100GB of ram usage). Needing to vertically scale nodes that use the index. But it’s still very fast and good. I wouldn’t call it “dangerous” just “expensive”.

Interestingly though, I found that usearch package worked great and let me split and offload indexes into separate files on disk, greatly lowered ram usage and latency is still quite good on average, but has some spikes (eg. sometimes when doing nearest 10k though can be ~1-3 seconds on the 200M dataset)