XML数据实体化视图自维护判定准则

Self-maintainability criterion of materialized views over XML data

为利用视图自维护技术提高可扩展标记语言(XML)数据实体化视图维护性能,提出XML数据视图自维护判定准则.采用WHAX数据模型及其查询语言WHAXQL作为XML数据模型及查询语言,分析了WHAXQL的重构能力,讨论了自维护问题的定义,设定视图的外延是可读取的,采用最小Z划分对绑定模式进行划分,将绑定模式变量分为显式变量和隐式变量,分别给出插入和删除更新操作时XML实体化数据视图自维护的充分必要条件,给出严格的证明,得到相应更新操作下的自维护算法.结果表明,该维护准则和算法能够用来作为XML实体化数据自维护的判定依据.

To improve the performance of extensible markup language (XML) data materialized view maintenance by utilizing self-maintenance technique, the self-maintainability criterion of materialized views of XML data was proposed. Warehouse architecture for XML (WHAX) data model and the corresponding query language WHAX-QL were adopted as the XML data model and corresponding query language respectively, and the WHAX-QL reconstruction ability was discussed. Assuming XML data materialized view extension to be accessible, the binding patterns were divided into subsets, and the binding variables were classified into public and private variables. The criterion determining self-maintainability under the operator of insertion and deletion were proposed, and the necessary and sufficient conditions of XML materialized data self-maintainability under insertion and deletion update operators were rigidly proved. The corresponding efficient algorithms to implement self-maintenance of views for XML data were presented also. Results show that the criterion and the algorithm can be used to determine the self-maintainability.