Optimizing SSD-Resident Graph Indexing for High-Throughput Vector Search

Fuente: arXiv
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Main Authors: Zhao, Weichen, Lu, Yuncheng, Tian, Yao, Zhang, Hao, Li, Jiehui, Zhao, Minghao, Li, Yakun, Qian, Weining
Format: Preprint
Published: 2026
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author Zhao, Weichen
Lu, Yuncheng
Tian, Yao
Zhang, Hao
Li, Jiehui
Zhao, Minghao
Li, Yakun
Qian, Weining
author_facet Zhao, Weichen
Lu, Yuncheng
Tian, Yao
Zhang, Hao
Li, Jiehui
Zhao, Minghao
Li, Yakun
Qian, Weining
contents Graph-based approximate nearest neighbor search (ANNS) methods (e.g., HNSW) have become the de facto state of the art for their high precision and low latency. To scale beyond main memory, recent out-of-memory ANNS systems leverage SSDs to store large vector indexes. However, they still suffer from severe CPU underutilization and read amplification (i.e., storage stalls) caused by limited access locality during graph traversal. We present VeloANN, which mitigates storage stalls through a locality-aware data layout and a coroutine-based asynchronous runtime. VeloANN utilizes hierarchical compression and affinity-based data placement scheme to co-locate related vectors within the same page, effectively reducing fragmentation and over-fetching. We further design a record-level buffer pool, where each record groups the neighbors of a vector; by persistently retaining hot records in memory, it eliminates excessive page swapping under constrained memory budgets. To minimize CPU scheduling overheads during disk I/O interruptions, VeloANN employs a coroutine-based asynchronous runtime for lightweight task scheduling. On top of this, it incorporates asynchronous prefetching and a beam-aware search strategy to prioritize cached data, ultimately improving overall search efficiency. Extensive experiments show that VeloANN outperforms state-of-the-art disk-based ANN systems by up to 5.8x in throughput and 3.25x in latency reduction, while achieving 0.92x the throughput of in-memory systems using only 10% of their memory footprint.
format Preprint
id arxiv_https___arxiv_org_abs_2602_22805
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Optimizing SSD-Resident Graph Indexing for High-Throughput Vector Search
Zhao, Weichen
Lu, Yuncheng
Tian, Yao
Zhang, Hao
Li, Jiehui
Zhao, Minghao
Li, Yakun
Qian, Weining
Databases
Graph-based approximate nearest neighbor search (ANNS) methods (e.g., HNSW) have become the de facto state of the art for their high precision and low latency. To scale beyond main memory, recent out-of-memory ANNS systems leverage SSDs to store large vector indexes. However, they still suffer from severe CPU underutilization and read amplification (i.e., storage stalls) caused by limited access locality during graph traversal. We present VeloANN, which mitigates storage stalls through a locality-aware data layout and a coroutine-based asynchronous runtime. VeloANN utilizes hierarchical compression and affinity-based data placement scheme to co-locate related vectors within the same page, effectively reducing fragmentation and over-fetching. We further design a record-level buffer pool, where each record groups the neighbors of a vector; by persistently retaining hot records in memory, it eliminates excessive page swapping under constrained memory budgets. To minimize CPU scheduling overheads during disk I/O interruptions, VeloANN employs a coroutine-based asynchronous runtime for lightweight task scheduling. On top of this, it incorporates asynchronous prefetching and a beam-aware search strategy to prioritize cached data, ultimately improving overall search efficiency. Extensive experiments show that VeloANN outperforms state-of-the-art disk-based ANN systems by up to 5.8x in throughput and 3.25x in latency reduction, while achieving 0.92x the throughput of in-memory systems using only 10% of their memory footprint.
title Optimizing SSD-Resident Graph Indexing for High-Throughput Vector Search
topic Databases
url https://arxiv.org/abs/2602.22805