SAQ: Pushing the Limits of Vector Quantization through Code Adjustment and Dimension Segmentation

Fuente: arXiv
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Hauptverfasser: Li, Hui, Deng, Shiyuan, Yan, Xiao, Zhi, Xiangyu, Cheng, James
Format: Preprint
Veröffentlicht: 2025
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author Li, Hui
Deng, Shiyuan
Yan, Xiao
Zhi, Xiangyu
Cheng, James
author_facet Li, Hui
Deng, Shiyuan
Yan, Xiao
Zhi, Xiangyu
Cheng, James
contents Approximate Nearest Neighbor Search (ANNS) plays a critical role in applications such as search engines, recommender systems, and RAG for LLMs. Vector quantization (VQ), a crucial technique for ANNS, is commonly used to reduce space overhead and accelerate distance computations. However, despite significant research advances, state-of-the-art VQ methods still face challenges in balancing encoding efficiency and quantization accuracy. To address these limitations, we propose a novel VQ method called SAQ. To improve accuracy, SAQ employs a new dimension segmentation technique to strategically partition PCA-projected vectors into segments along their dimensions. By prioritizing leading dimension segments with larger magnitudes, SAQ allocates more bits to high-impact segments, optimizing the use of the available space quota. An efficient dynamic programming algorithm is developed to optimize dimension segmentation and bit allocation, ensuring minimal quantization error. To speed up vector encoding, SAQ devises a code adjustment technique to first quantize each dimension independently and then progressively refine quantized vectors using a coordinate-descent-like approach to avoid exhaustive enumeration. Extensive experiments demonstrate SAQ's superiority over classical methods (e.g., PQ, PCA) and recent state-of-the-art approaches (e.g., LVQ, Extended RabitQ). SAQ achieves up to 80% reduction in quantization error and accelerates encoding speed by over 80x compared to Extended RabitQ.
format Preprint
id arxiv_https___arxiv_org_abs_2509_12086
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SAQ: Pushing the Limits of Vector Quantization through Code Adjustment and Dimension Segmentation
Li, Hui
Deng, Shiyuan
Yan, Xiao
Zhi, Xiangyu
Cheng, James
Databases
Data Structures and Algorithms
Information Retrieval
Approximate Nearest Neighbor Search (ANNS) plays a critical role in applications such as search engines, recommender systems, and RAG for LLMs. Vector quantization (VQ), a crucial technique for ANNS, is commonly used to reduce space overhead and accelerate distance computations. However, despite significant research advances, state-of-the-art VQ methods still face challenges in balancing encoding efficiency and quantization accuracy. To address these limitations, we propose a novel VQ method called SAQ. To improve accuracy, SAQ employs a new dimension segmentation technique to strategically partition PCA-projected vectors into segments along their dimensions. By prioritizing leading dimension segments with larger magnitudes, SAQ allocates more bits to high-impact segments, optimizing the use of the available space quota. An efficient dynamic programming algorithm is developed to optimize dimension segmentation and bit allocation, ensuring minimal quantization error. To speed up vector encoding, SAQ devises a code adjustment technique to first quantize each dimension independently and then progressively refine quantized vectors using a coordinate-descent-like approach to avoid exhaustive enumeration. Extensive experiments demonstrate SAQ's superiority over classical methods (e.g., PQ, PCA) and recent state-of-the-art approaches (e.g., LVQ, Extended RabitQ). SAQ achieves up to 80% reduction in quantization error and accelerates encoding speed by over 80x compared to Extended RabitQ.
title SAQ: Pushing the Limits of Vector Quantization through Code Adjustment and Dimension Segmentation
topic Databases
Data Structures and Algorithms
Information Retrieval
url https://arxiv.org/abs/2509.12086