Collaborative Research: The REVELATION Project: Query Processing in Behavioral Object-Oriented Databases

正在开发许多新的数据管理系统，以支持具有高级数据管理需求的应用程序，例如扩展关系模型、持久编程语言和面向对象数据库。这样的系统增强了语义表达能力，但它们必须提供良好的性能才能成为可行的商业技术。一个特别需要改进性能的领域是查询处理，其中新的建模特性，如封装、类型层次结构、复杂值和对象标识，使传统的集处理方法难以应用或无效。Revelation项目的总体目标是扩展查询处理，以便在查询处理的所有层次（从模式管理到优化和物理规划，再到运行时支持）中处理和利用这些新的建模扩展。为了进行封装，我们加入了一个揭示器，一个可以访问类型实现的可信系统组件。由子类型和多态性引起的集合中的异构性由跨模式定义进行推理的Annotater处理。复杂的值和单位在逻辑代数级别上，通过处理有序结构（如序列和数组）的新操作，以及在物理级别上通过新的操作符（如组装复杂对象的操作符）来处理。该项目将构建一个原型查询处理器，利用现有的软件技术，如Volcano优化器生成器和Volcano查询评估系统。

Many new data management systems are being developed to support applications with advanced data management requirements, such as extended relational models, persistent programming languages and object-oriented databases. Such systems enhance semantic expressiveness, but they must offer good performance to be viable commercial technologies. An area particularly needful of improved performance is query processing, where new modeling features such as encapsulation, type hierarchies, complex values and object identity make conventional set-processing methods difficult or ineffective to apply. The overall goal of the Revelation project is to expand query processing to address and exploit these new modeling extensions at all levels of query processing, from schema management, through optimization and physical planning, to runtime support. For encapsulation, a Revealer is incorporated, a trusted system component that can access type implementations. Heterogeneity in collections arising from subtyping and polymorphism is handled by an Annotater that reasons across schema definitions. Complex values and identity are addressed both at the logical algebra level, with new operations to deal with ordered structures such as sequences and arrays, and at the physical level with new operators such as one to assemble complex objects. This project will construct a prototype query processor, exploiting existing software technology such as the Volcano optimizer generator and the Volcano query evaluation system.