Advanced query language for manipulating complex entities

摘要

Complex entities are one of the most popular ways to model relationships among data. Especially complex entities, known as physical assemblies, are popular in several applications. Typically, complex entities consist of several parts organized at many nested levels. Contemporary query languages intended for manipulating complex entities support only extensional queries. Likewise, the user has to master the structures of complex entities completely, which is impossible if a physical assembly consists of a huge number of parts. Further, query languages do not support the manipulation of documents related to parts of physical assemblies. In this paper we introduce a novel, declarative and powerful query language, in which the above deficiencies have been eliminated. Our query language supports text information retrieval related to parts and it contains intensional and combined extensional–intensional query features. These features support making queries of new types. In the paper we give several sample queries, which demonstrate the usefulness of these query types. In addition, we show that conventional extensional queries can be formulated intuitively and compactly in our query language. Among other things this is due to our query primitives allowing removal of the explicit specification of navigation from the user.