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arXiv 2304.05028cs.DB
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列式存储格式的实证评估

An Empirical Evaluation of Columnar Storage Formats

Xinyu Zeng, Yulong Hui, Jiahong Shen, Andrew Pavlo, Wes McKinney, Huanchen Zhang

AI总结:

该研究针对硬件与工作负载变迁的背景,深入评估Parquet和ORC两种主流开源列式存储格式,识别出适配现代环境的设计优化点与现存低效问题,为新一代存储格式的设计提供参考。

摘要:

列式存储是现代数据分析系统的核心组件。尽管许多数据库管理系统(DBMS)拥有专有存储格式,但大多数都对Parquet和ORC等开源存储格式提供广泛支持,以促进跨平台数据共享。但这些格式是十多年前(2010年代初)为Hadoop生态系统开发的,此后硬件和工作负载格局都已发生变化。\n本文重新审视了应用最广泛的开源列式存储格式Parquet和ORC,深入探究其内部结构。我们设计了一个基准测试,在不同工作负载配置下对这些格式的性能和空间效率进行压力测试。通过对Parquet和ORC的全面评估,我们确定了适配现代硬件和真实世界数据分布的优化设计决策,包括默认使用字典编码、在整数编码算法中优先考虑解码速度而非压缩比、将块压缩设为可选,以及嵌入更细粒度的辅助数据结构。我们还指出了格式设计在处理常见机器学习工作负载和使用GPU解码时的低效问题。我们的分析确定了重要的考量因素,可指导未来的格式更好地适配现代技术趋势。

英文摘要:

Columnar storage is a core component of a modern data analytics system. Although many database management systems (DBMSs) have proprietary storage formats, most provide extensive support to open-source storage formats such as Parquet and ORC to facilitate cross-platform data sharing. But these formats were developed over a decade ago, in the early 2010s, for the Hadoop ecosystem. Since then, both the hardware and workload landscapes have changed. In this paper, we revisit the most widely adopted open-source columnar storage formats (Parquet and ORC) with a deep dive into their internals. We designed a benchmark to stress-test the formats' performance and space efficiency under different workload configurations. From our comprehensive evaluation of Parquet and ORC, we identify design decisions advantageous with modern hardware and real-world data distributions. These include using dictionary encoding by default, favoring decoding speed over compression ratio for integer encoding algorithms, making block compression optional, and embedding finer-grained auxiliary data structures. We also point out the inefficiencies in the format designs when handling common machine learning workloads and using GPUs for decoding. Our analysis identified important considerations that may guide future formats to better fit modern technology trends.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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