多媒体数据库的时态索引技术

针对多媒体数据库中具有时态特性的媒体对象，提出一种基于区间的索引机制，目的是为了提高时间检索的性能。这种时态索引可以快速查找任意时间段中的时态对象，它能有效地支持多种时态关系操作符；支持多种时态集函数；支持时态ＪＯＩＮ操作等等。该索引支持媒体展示过程。

Structural Indexing of Organized Multimedia Objects

The development of information technology provides the accessibility to enormous numbers of multimedia objects, simple and complex. Indexing of multimedia objects has become a crucial issue. The variety of multimedia data model, the low efficiency of content based searching, and the lack of proper query language all have made multimedia indexing a difficult subject. The multimedia indexing project recently carried by the University of Kent at Canterbury (UK) has made a breakthrough in the related areas. The virtual database developed in the project provides users a tool to create and maintain a private view of interesting multimedia objects. The virtual database is organized in a hierarchical structure. The multimedia object references it stored are associated with a set of attributes called `cues' which are used in the browsing agent for constructing query conditions. The browsing agent performs the searching process on the user's behalf. Users first tell the agent how to find and recognize interesting objects, then set it going and control the query evaluation. The query specified by the user includes a framework, which plays the role of navigator in the evaluation process, and a collection of embedded queries. The browsing agent evaluates the query by checking the object cues stored in the virtual database and by calling individual external evaluators.