Non-cryptographic

t1ha (Fast Positive Hash)

Designed by Leonid Yuriev (2016+). The full name “Fast Positive Hash” emphasizes both speed and clean SMHasher bias results. The t1ha family sits in the same speed tier as xxHash3 and CityHash, with slightly different optimization choices for different CPU microarchitectures.

The variants

• t1ha0 , portable baseline; works on any 32 / 64-bit CPU.
• t1ha1 , 64-bit-tuned, classic implementation.
• t1ha2 , updated mixer, 64 / 128-bit output.
• t1ha3 , experimental high-speed variant.
• t1ha0_ia32aes , AES-NI-accelerated variant.

At a glance

Where it shows up

• libmdbx , high-performance key-value storage (Yuriev’s own project) uses t1ha.
• ClickHouse , supports t1ha as a SQL hash function.
• Some Russian financial / database backends.
• SMHasher benchmark , canonical reference results.

vs xxHash3 and CityHash

On modern Intel / AMD CPUs, t1ha and xxHash3 trade leadership depending on input size and exact instruction set. The choice in practice is ecosystem-driven: pick the hash your platform’s community has the most tooling for. SMHasher distribution scores are competitive across the three.

References

• erthink/t1ha source repository
• SMHasher fork , benchmarks t1ha alongside competitors
• xxHash3 · MurmurHash3