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Main Authors: Domes, Tomáš, Veselý, Pavel
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.17396
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author Domes, Tomáš
Veselý, Pavel
author_facet Domes, Tomáš
Veselý, Pavel
contents Quantile summaries provide a scalable way to estimate the distribution of individual attributes in large datasets that are often distributed across multiple machines or generated by sensor networks. ReqSketch (arXiv:2004.01668) is currently the most space-efficient summary with two key properties: relative error guarantees, offering increasingly higher accuracy towards the distribution's tails, and mergeability, allowing distributed or parallel processing of datasets. Due to these features and its simple algorithm design, ReqSketch has been adopted in practice, via implementation in the Apache DataSketches library. However, the proof of mergeability in ReqSketch is overly complicated, requiring an intricate charging argument and complex variance analysis. In this paper, we provide a refined version of ReqSketch, by developing so-called adaptive compactors. This enables a significantly simplified proof of relative error guarantees in the most general mergeability setting, while retaining the original space bound, update time, and algorithmic simplicity. Moreover, the adaptivity of our sketch, together with the proof technique, yields near-optimal space bounds in specific scenarios - particularly when merging sketches of comparable size.
format Preprint
id arxiv_https___arxiv_org_abs_2511_17396
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Relative Error Streaming Quantiles with Seamless Mergeability via Adaptive Compactors
Domes, Tomáš
Veselý, Pavel
Data Structures and Algorithms
Quantile summaries provide a scalable way to estimate the distribution of individual attributes in large datasets that are often distributed across multiple machines or generated by sensor networks. ReqSketch (arXiv:2004.01668) is currently the most space-efficient summary with two key properties: relative error guarantees, offering increasingly higher accuracy towards the distribution's tails, and mergeability, allowing distributed or parallel processing of datasets. Due to these features and its simple algorithm design, ReqSketch has been adopted in practice, via implementation in the Apache DataSketches library. However, the proof of mergeability in ReqSketch is overly complicated, requiring an intricate charging argument and complex variance analysis. In this paper, we provide a refined version of ReqSketch, by developing so-called adaptive compactors. This enables a significantly simplified proof of relative error guarantees in the most general mergeability setting, while retaining the original space bound, update time, and algorithmic simplicity. Moreover, the adaptivity of our sketch, together with the proof technique, yields near-optimal space bounds in specific scenarios - particularly when merging sketches of comparable size.
title Relative Error Streaming Quantiles with Seamless Mergeability via Adaptive Compactors
topic Data Structures and Algorithms
url https://arxiv.org/abs/2511.17396