Clark Hash: Stateless Sparse Johnson-Lindenstrauss Quantization for Neural Embeddings

Fuente: arXiv
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Autores principales: Kirdey, Stanislav, Inc, Clark Labs
Formato: Preprint
Publicado: 2026
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author Kirdey, Stanislav
Inc, Clark Labs
author_facet Kirdey, Stanislav
Inc, Clark Labs
contents Clark Hash is a small method for storing neural embeddings in less space. It normalizes each database vector, applies a deterministic sparse signed Johnson-Lindenstrauss projection, clips the result, and stores a fixed-width scalar-quantized code. Queries stay in floating point and are scored against the stored sketches. In the default 384-dimensional sentence-embedding setting, Clark Hash stores a cosine-search vector in 48 bytes instead of 1536 bytes for dense f32 storage. This is 32x smaller. The method does not need a training pass, learned codebooks, rotations, or corpus statistics before new vectors can be stored. We describe the codec, the Rust implementation, and a multilingual sentence-similarity evaluation on 9,304 labeled pairs from 29 subsets. With a multilingual MiniLM encoder, the 48-byte sketches reached 0.910 and 0.946 macro Pearson correlation with dense cosine scores on STS17 and STS22. Clark Hash is not a new Johnson-Lindenstrauss theorem and it is not a replacement for approximate nearest-neighbor indexes. It is a simple stateless codec for compact embedding storage.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28034
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Clark Hash: Stateless Sparse Johnson-Lindenstrauss Quantization for Neural Embeddings
Kirdey, Stanislav
Inc, Clark Labs
Artificial Intelligence
H.3.3; E.4
Clark Hash is a small method for storing neural embeddings in less space. It normalizes each database vector, applies a deterministic sparse signed Johnson-Lindenstrauss projection, clips the result, and stores a fixed-width scalar-quantized code. Queries stay in floating point and are scored against the stored sketches. In the default 384-dimensional sentence-embedding setting, Clark Hash stores a cosine-search vector in 48 bytes instead of 1536 bytes for dense f32 storage. This is 32x smaller. The method does not need a training pass, learned codebooks, rotations, or corpus statistics before new vectors can be stored. We describe the codec, the Rust implementation, and a multilingual sentence-similarity evaluation on 9,304 labeled pairs from 29 subsets. With a multilingual MiniLM encoder, the 48-byte sketches reached 0.910 and 0.946 macro Pearson correlation with dense cosine scores on STS17 and STS22. Clark Hash is not a new Johnson-Lindenstrauss theorem and it is not a replacement for approximate nearest-neighbor indexes. It is a simple stateless codec for compact embedding storage.
title Clark Hash: Stateless Sparse Johnson-Lindenstrauss Quantization for Neural Embeddings
topic Artificial Intelligence
H.3.3; E.4
url https://arxiv.org/abs/2605.28034