arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1409.6288cs.DB
收藏

启用增量查询重新优化

Enabling Incremental Query Re-Optimization

Mengmeng Liu, Zachary G. Ives, Boon Thau Loo

摘要:

随着声明式查询处理技术的范围扩展到Web、数据流、网络路由器和云平台,人们越来越需要自适应查询处理技术,这些技术可以在出现故障或意外性能变化时重新规划。数据分布或计算节点上的状态更新可能会对应该运行哪个查询计划的选择产生重大影响。理想情况下,新的系统架构将能够基于成本做出关于重新分配工作、迁移数据等的决策,并在实时状态信息可用时快速做出反应。现有的基于成本的查询优化器本质上不是增量的,并且必须在每次状态或成本更新时“从头开始”运行。因此,它们通常导致只能缓慢地对更新做出反应的自适应方案。一个悬而未决的问题是,是否有可能在流式或重复查询执行环境中构建用于自适应查询处理的基于成本的重新优化架构,例如,通过在给定新成本信息的情况下递增地更新优化器状态。我们表明,这可以实现有益的,特别是流处理工作负载。我们的技术建立在最近提出的方法,制定查询计划枚举作为一组递归的数据库查询,我们开发了各种新的优化方法,以确保有效的修剪在静态和增量的情况下。我们实现我们的解决方案在现有的研究查询处理系统,并表明,它有效地支持基于成本的初始优化以及频繁的自适应性。

英文摘要:

As declarative query processing techniques expand in scope --- to the Web, data streams, network routers, and cloud platforms --- there is an increasing need for adaptive query processing techniques that can re-plan in the presence of failures or unanticipated performance changes. A status update on the data distributions or the compute nodes may have significant repercussions on the choice of which query plan should be running. Ideally, new system architectures would be able to make cost-based decisions about reallocating work, migrating data, etc., and react quickly as real-time status information becomes available. Existing cost-based query optimizers are not incremental in nature, and must be run "from scratch" upon each status or cost update. Hence, they generally result in adaptive schemes that can only react slowly to updates. An open question has been whether it is possible to build a cost-based re-optimization architecture for adaptive query processing in a streaming or repeated query execution environment, e.g., by incrementally updating optimizer state given new cost information. We show that this can be achieved beneficially, especially for stream processing workloads. Our techniques build upon the recently proposed approach of formulating query plan enumeration as a set of recursive datalog queries; we develop a variety of novel optimization approaches to ensure effective pruning in both static and incremental cases. We implement our solution within an existing research query processing system, and show that it effectively supports cost-based initial optimization as well as frequent adaptivity.

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。

↑