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首页> 外文会议>Twenty-Seventh International Conference on Very Large Data Bases, 27th, Sep 11-14th, 2001, Roma, Italy >Query Engines for Web-Accessible XML Data
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Query Engines for Web-Accessible XML Data

机译：Web可访问的XML数据查询引擎

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摘要

Even though XML was first introduced as a schema-less, self-describing data representation language, there are now proposals for XML schema descriptions. The addition of schema information opens new opportunities in using the already established database management technology for storing and handling XML data, since databases are traditionally focused on data that conform to a fixed, predefined schema. Schema information allows better data integrity, more effective data storage, and more efficient query evaluation. This paper describes an effective framework for storing XML data in an object-oriented database and an optimization framework for translating XML queries into efficient algorithms. We first present a new type system for describing XML data, well integrated with the ODL type system of the ODMG standard, that captures both schema-less (semi-structured) and schema-based XML data. We then introduce a small set of syntactic extensions to ODMG OQL, powerful enough to make OQL a full-fledged XML query language. Next, we present a framework for translating XML queries into OQL queries based on XML schema information. Instead of inventing yet another semi-structured algebra for expressing our translations, the target of our transformation rules is OQL code, which not only has precise semantics, but has also been the focus of various optimization techniques. Schema information is an indispensable component of our transformations. It is used in disambiguating terms with multiple interpretations such as wildcard tag projections, in choosing the storage format for the XML data, and in generating OQL code guided by the choice of storage.
机译：尽管XML最初是作为一种无模式的，自我描述的数据表示语言而引入的，但现在仍提出了XML模式描述的建议。模式信息的添加为使用已经建立的数据库管理技术存储和处理XML数据提供了新的机会，因为传统上数据库专注于遵循固定的预定义模式的数据。模式信息可提供更好的数据完整性，更有效的数据存储和更有效的查询评估。本文描述了一种用于在面向对象的数据库中存储XML数据的有效框架，以及一种用于将XML查询转换为高效算法的优化框架。我们首先介绍一种用于描述XML数据的新型系统，该系统与ODMG标准的ODL类型系统很好地集成在一起，可以捕获无模式（半结构化）和基于模式的XML数据。然后，我们为ODMG OQL引入了少量语法扩展，其功能强大到足以使OQL成为成熟的XML查询语言。接下来，我们提供一个基于XML模式信息将XML查询转换为OQL查询的框架。代替发明另一个用于表达翻译的半结构代数，我们的转换规则的目标是OQL代码，它不仅具有精确的语义，而且还是各种优化技术的重点。模式信息是我们转换中必不可少的组成部分。它用于消除通配符标记投影等多种解释的歧义，选择XML数据的存储格式，以及在存储选择的指导下生成OQL代码。

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