Client and method for database

摘要

A client accepts 20 an input query, rewrites 22 the query and forwards 24 the query to a database server, which returns 26 results which are then rewritten 28. The database includes classes arranged hierarchically as superclasses and subclasses, and/or properties also arranged hierarchically as superproperties and subproperties. In embodiments, the query is rewritten 22 to replace each instance of each class and each property in the input query with the transitive closure of the respective class or property. The client allows inferencing whether or not this is supported by the database server.

主权项

1. A method of operating a client for a database system, the database system having a server which stores data in the form of data items and properties of the data items, wherein the data items are grouped into classes, wherein at least one of relations between properties and relations between classes are defined, relations between properties being defined as directed links linking pairs of properties as superproperty and subproperty, the subproperty inheriting from the superproperty and from any properties from which the superproperty inherits, relations between classes being defined as directed links between pairs of classes, each pair including a superclass and a subclass, the subclass inheriting from the superclass and from any classes from which the superclass inherits, the method comprising:
accepting an input query including at least one reference to a property or at least one reference to a class; rewriting at the client the input query as a rewritten query by including together with a reference to a property that is a superproperty a reference to one or more properties which inherit from the superproperty and/or including together with a reference to a class that is a superclass a reference to one or more classes which inherit from the superclass; sending the rewritten query from the client to the database server; and receiving results from the server.