The CQL continuous query language: semantic foundations and query execution
The CQL continuous query language: semantic foundations and query execution
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DOI：
10.1007/s00778-004-0147-z
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发表时间：
2006-06-01
期刊：
影响因子：
4.2
通讯作者：
Widom, J
中科院分区：
文献类型：
--
作者：
Arasu, A;Babu, S;Widom, J
CQL是一种构成的查询语言，得到了斯坦福大学的流原型数据流管理系统（DSM）的支持。 CQL是一种基于表达的SQL的声明语言，用于注册针对流和存储关系的连续查询。我们首先提出一个抽象的语义，该语义仅依赖于流和关系之间的“黑框”映射。从这些映射中，我们为连续查询定义了一种精确的一般解释。 CQL是使用SQL对我们的抽象语义的实例化，以映射从关系到关系，从SQL-99到从流到关系的映射的窗口规范，以及三个新运算符到从关系到流的映射。大多数CQL语言都在流系统中运行。我们介绍了CQL查询执行计划的结构以及最重要的组成部分的详细信息：操作员，互操作者队列，摘要，以及在多个操作员和查询中共享组件。本文中的示例是从最近提出的DSMS的线性道路基准中绘制的。我们还策划了一个数据流应用程序的公共存储库，其中包括CQL中表达的各种查询。在CQL中捕获这些应用程序的相对容易性是该语言包含适当的数据流处理构造集。
CQL, a contintious query language, is supported by the STREAM prototype data stream management system (DSMS) at Stanford. CQL is an expressive SQL-based declarative language for registering continuous queries against streams and stored relations. We begin by presenting an abstract semantics that relies only on "black-box" mappings among streams and relations. From these mappings we define a precise and general interpretation for continuous queries. CQL is an instantiation of our abstract semantics using SQL to map from relations to relations, window specifications derived from SQL-99 to map from streams to relations, and three new operators to map from relations to streams. Most of the CQL language is operational in the STREAM system. We present the structure of CQL's query execution plans as well as details of the most important components: operators, interoperator queues, synopses, and sharing of components among Multiple operators and queries. Examples throughout the paper are drawn from the Linear Road benchmark recently proposed for DSMSs. We also curate a public repository of data stream applications that includes a wide variety of queries expressed in CQL. The relative ease of capturing these applications in CQL is one indicator that the language contains an appropriate set of constructs for data stream processing.