An Effective Framework for Processing OODB Languages

关系数据模型的一个被大肆吹捧的优点是，存在一种形式演算和代数来对数据库查询进行建模。在实践中，这些形式化不能对商业查询语言（例如SQL）中的许多特性进行建模：分组、聚合、重复值和排序顺序。当转向面向对象的查询语言（如ODMG-93的OQL）时，差距只会扩大，它必须处理多个批量（集合）类型、类型构造函数的任意嵌套、方法和嵌入式查询表达式。这些特性也出现在关系查询语言标准提案中，比如SQL3。这项工作解决了现代数据库语言的高效查询处理。它试图通过原型实现证明，如果在查询演算中直接支持新的语言特性，则可以更有效地处理这些特性。本文的研究框架就是建立在这样一个微积分的基础上的，这个微积分被称为一元理解微积分。我们的形式化模型不是从关系代数开始进行扩展，而是自然地表示数据库语言的新出现的特性。该研究的成功成果将为实现纯面向对象模型和关系对象模型的商业数据库系统的查询处理器提供更好的基础

A much-touted advantage of the relational data model is the existence of a formal calculus and algebra to model database queries. In practice, these formalisms fail to model many of the features present in commercial query languages (e.g., SQL): grouping, aggregation, duplicate values, and sort orders. The gap only widens as one moves to object- oriented query languages, such as OQL of ODMG-93, which must deal with multiple bulk (collection) types, arbitrary nesting of type constructors, methods and embedded query expressions. Such features also appear in relational query language standards proposals, such as SQL3. This work addresses efficient query processing for modern database languages. It seeks to demonstrate through prototype implementation that new language features can be handled more effectively if these features have direct support in a query calculus. The research framework is based on such a calculus, called the monoid comprehension calculus. Instead of starting from relational algebra and making extensions, our formal model represents naturally the new emerging features of database lang uages. A successful outcome for the research will lead to a better basis for implementing the query processors of commercial database systems, both of pure object-oriented models and relational-object