aHash VS FastHash

If you find yourself in a situation where you've got some kind of HashMap in your JSON data, try using ahash as the hasher... either via the ready-made ahash::AHashMap or via something like type AHashMap = std::collections::HashMap; if you're using something like serde_with which doesn't like the ready-made one.

aHash claims it is faster than t1ha[1].

The t1ha crate also hasn't been updated in over three years so the benchmark in this link should be current.

[1] https://github.com/tkaitchuck/aHash/blob/master/compare/read...

When I recently went shopping for fast hashes for short strings, I settled on wyhash, but ahash[0] seemed like it would have been better if I had bothered to port it from Rust.

> In that time you can FNV-1a a "short" string.

Not if you read it one byte at a time like in TFA!

It looks like the best FNV for short strings in smhasher[1] is comparably fast to ahash[2] on short strings, but I proposed doing slightly less work than ahash.

> From the top of my head, t1ha, falkhash, meowhash and metrohash are using AES-NI and none of them are particularly fast on short inputs, and at least two of them have severe issues, despite guarding against lots of vulnerabilities, which your construction does not.

For issues like reading past the ends of buffers and discarding the extra values, it would be nice if programmers could arrange to have buffers that could be used this way. I posted a thing for hashing strings of a fixed length though, to compare with the thing for hashing strings of a fixed length in TFA.

[0]: https://github.com/tkaitchuck/aHash/blob/master/src/aes_hash...

[1]: https://github.com/rurban/smhasher/blob/master/doc/FNV1a_YT....

[2]: https://github.com/rurban/smhasher/blob/master/doc/ahash64.t...

Regarding the hashing function: I'll already tried using aHash which sped thing things up but not by a lot.

aHash has a very good comparison doc: https://github.com/tkaitchuck/aHash/blob/master/compare/readme.md (Personally, I use it more to compare non-aHash hashes than to aHash; aHash has no reason to be biased between other hashes, though it does have reason to be biased for itself. I trust their analysis to not be biased, but it's always better to be more sure.)

Hi, i was under the impression that with resolver = "2" cargo would be able to respect the target for the dependencies. Currently i have the problem that while using sqlx, surf and gloo in projects that are in the same workspace – thus sharing a single Cargo.lock – i get a cyclic dependency with aHash that is roughly discussed here

Apparently there is a patch for the SMHasher here which adds support for ahash:

https://github.com/tkaitchuck/aHash/tree/master/smhasher

There are also ahash's own benchmarks here:

https://github.com/tkaitchuck/aHash/blob/master/compare/test...

They use the wyhash Rust crate, so if wyhash itself was updated doing a head to head comparison would boil down to updating the wyhash crate and rerunning ahash's benchmark suite.

I've implemented your RecSplit method in my MPHF benchmark library (written in C#). The suite is not yet public, but I do want to say thank you for your fantastic method/code/paper. In my own rabbithole research, I stumbled upon several artifacts of your rabbithole trail. Most notably the stuff on StackOverflow, which helped my own research.

I've releaed a set og fast hash functions[1] to help gain an understanding of speed vs. quality. My biggest takeaway is that most generic hash functions can be specialized for integer inputs[2], which often reduce latency by quite a lot, making MPFH more attractive over simple iteration on small sets, as the overhead of hashing is considerably smaller.

[1] https://github.com/Genbox/FastHash

[2] https://github.com/Genbox/FastHash/blob/master/src/FastHash/...

It was made (by Sanmayce) to optimize for instruction-level pipelining, and use the fact that modern CPUs have multiple execution ports. But due to those changes, it is not compatible with FNV1a anymore.

The trick of reading in stripes is employed by many of the fastest hashes. It is kinda funny to see how one author prefers a switch case over for loops, where others prefer while loops. The differences can sometimes have a big impact on what optimizations the compiler decides to use.

[1] https://github.com/Genbox/FastHash/blob/master/src/FastHash....

At the moment I'm working on FastHash[1], a pet project of mine to port a few high-performance non-cryptographic hash functions to C#.

I'm also trying to build FastLinq, a value-by-reference Language Integrated Query (LINQ) optimized for high-performance scenarios. It is kind of a weird mix as LINQ in .NET is known for its high overhead.

Finally, I'm working on an Office setting synchronization application. I heard a podcast with Paul Thurrott complaining about the lack of sync solutions, so I thought I would do one for fun.

[1] https://github.com/Genbox/FastHash