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arXiv 2409.17136cs.DB
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面向查询优化的自适应代价模型

Adaptive Cost Model for Query Optimization

Nikita Vasilenko, Alexander Demin, Denis Ponomaryov

AI总结:

针对数据库负载和系统性能变化导致传统静态代价模型参数失效的问题,提出自适应代价模型ACM,在DB运行时动态优化CPU和I/O代价参数,在TPC-H基准上实现20%的端到端延迟改善。

摘要:

传统数据库查询优化器的主要组件是代价模型,用于估计查询计划的预期性能。代价模型的准确性直接影响优化器所选执行计划的最优性,进而影响最终的查询延迟。现代DBMS中代价模型的几个常见参数与CPU和I/O的性能相关,通常由数据库管理员在系统调优时设置。然而,这些性能特征并不稳定,因此单点估计可能不足以应对所有DB负载状态。在本文中,我们提出了一种自适应代价模型(ACM),可在DB运行时动态优化与CPU和I/O相关的计划代价参数。通过持续监控查询执行统计信息和DB缓冲缓存的状态,ACM无需数据库管理员的手动干预即可调整代价参数。这使得系统能够响应工作负载和系统性能的变化,确保生成更优的查询执行计划。我们描述了ACM实现的主要思想,并报告了初步的实验评估结果,结果显示在TPC-H基准上实现了20%的端到端延迟改善。

英文摘要:

The principal component of conventional database query optimizers is a cost model that is used to estimate expected performance of query plans. The accuracy of the cost model has direct impact on the optimality of execution plans selected by the optimizer and thus, on the resulting query latency. Several common parameters of cost models in modern DBMS are related to the performance of CPU and I/O and are typically set by a database administrator upon system tuning. However these performance characteristics are not stable and therefore, a single point estimation may not suffice for all DB load regimes. In this paper, we propose an Adaptive Cost Model (ACM) which dynamically optimizes CPU- and I/O-related plan cost parameters at DB runtime. By continuously monitoring query execution statistics and the state of DB buffer cache ACM adjusts cost parameters without the need for manual intervention from a database administrator. This allows for responding to changes in the workload and system performance ensuring more optimal query execution plans. We describe the main ideas in the implementation of ACM and report on a preliminary experimental evaluation showing 20\% end-to-end latency improvement on TPC-H benchmark.

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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