Integrating and querying information sources in the context of large-scale ontological knowledge

信息丰富，商业上可行的具有大容量存储的计算机系统的引入有助于管理信息，这促进了数据库系统和底层技术的发展。到目前为止，最成功的是基于关系数据模型的系统。这样的系统为托管信息提供了一个清晰的概念领域特定接口。这使应用程序开发人员不必了解现有数据源及其物理数据组织的底层接口，也不必选择适当的数据结构和算法。因此，对于关系数据库系统，为数据操作请求（称为查询和更新）发现有效的执行策略（称为计划）一直是三十多年来的研究重点。

Information abounds, and the introduction of commercially viable computer systems with mass storage to help manage information has prompted the development of database systems together with an underlying technology. By far the most successful are systems that are based on the relational data model. Such systems provide a clean conceptual domain specific interface to managed information. This shields application developers from the need to understand low level interfaces to existing data sources and their physical data organization and from the need to choose appropriate data structures and algorithms. Hence, for relational database systems, discovering efficient execution strategies, called plans, for data manipulation requests, called queries and updates, has been the focus of research for more than thirty years.