SPTAG VS usearch

Code for https://arxiv.org/abs/2111.08566 found: https://github.com/microsoft/SPTAG

Another worth mentioning in this thread is usearch, though not a separate algorithm, based on HNSW with a bunch of optimizations https://github.com/unum-cloud/usearch

I've used usearch successfully for a small project: https://github.com/unum-cloud/usearch/

The hardest (still missing) part of efficient cosine computation distance computation is picking a good epsilon for the `sqrt` calculation and avoiding "division by zero" problems.

We have an open issue about it in USearch and a related one in SimSIMD itself, so if you have any suggestions, please share your insights - they would impact millions of devices using the library (directly on servers and mobile, and through projects like ClickHouse and some of the Google repos): https://github.com/unum-cloud/usearch/issues/320

As you scale, you may benefit from these two projects I maintain, and the Big Tech uses :)

https://github.com/unum-cloud/usearch - for faster search

https://github.com/unum-cloud/uform - for cheaper multi-lingual multi-modal embeddings

> It doesn't appear to query CPUID

Yes, I'm actually looking for a good way to do it for other projects as well. I've looked into a couple more libs, and here is the best I've come up with so far: https://github.com/unum-cloud/usearch/blob/f942b6f334b31716f...

> Your substring routines have multiplicative worst case

Yes, that is true. It's a very simple stupid trick, just happens to work well for me :)

> It seems quite likely that your confirmation step

We have a different library internally at Unum, that avoids this shortcoming. It has a few thousand lines of C++ templates with SIMD intrinsics... and it's definitely more efficient, but the margins aren't always high. So I kept the pure C version with inlined functions as minimal and simple as possible.

> It would actually be possible to hook Stringzilla up to `memchr`'s benchmark suite if you were interested. :-)

Yes, that would be a fun thing to do! I haven't had time to look into `memchr` yet, but would expect great perf from your lib as well. For me the State of the Art is Intel HyperScan. Probably the most advanced SIMD library overall, not just for strings. I was very impressed with their perf ~5 years ago. But the repo is 200 K LOC... So get ready to invest a weekend :)

That said, I'm a bit slammed with work right now, including open-source. Hoping to ship a new major release in UCall this week, and a minor one in USearch :)

We don't use BLAS. Why? BLAS helps with matrix-matrix multiplications, if you feel lazy and don't want to write the matrix tiling code manually.

They bring essentially nothing of value in vector-vector operations, as compilers can properly auto-vectorize simple dot products... Moreover, they generally only target single and double precision, while we often prefer half or quarter precision. All in all, meaningless dependency.

What do we use? I wrote a tiny package called SimSIMD. It's idea is to utilize less common SIMD instructions, especially in mixed-typed computations, that are hard for compilers to optimize. It was also a fun exercise to evaluate the performance of new SVE instruction on recent Arm CPUs, like the Graviton 3. You can find the code, the benchmarks, and the results in the repo: https://github.com/ashvardanian/simsimd

Still, even without SimSIMD, USearch seems to be one of the faster implementations of vector search. You can find the benchmarks in the first table here: https://github.com/unum-cloud/usearch#memory-efficiency-down...