面向对象XML数据索引技术

提出了一种面向对象XML数据的索引模式路径仓,路径仓是紧凑地、准确地表示面向对象的XML数据的一棵树,是两级双向树:组级和元素级.在组级上,路径仓提供路径信息、类层次信息,类层次信息存储以索引类为根的类层次子树上特有的元素和属性的对象标识符,而继承的元素和属性的对象标识符存在较高的层次中,可以在查询早期阶段减少大量存储空间;在元素级,它保存从孩子元素到父亲元素的信息,快速存取元素的父亲,提高查询处理效率.不使用全局标志符而是用基于组的引用,可以按组区分不同类型的元素值聚簇相同类型元素值并且索引它们.

An Indexing Technique for Object-Oriented XML Data

Path repository is proposed as a novel indexing scheme for object-oriented XML data,which is a bi-level tree to represent compactly and precisely the objectoriented XML data and composed of a group level and element level. At the group level,the path repository provides path summaries and class hierarchies,to store the element/attribute OIDs which are the specific information owned by the subtree rooted in index class, while the element/attribute OIDs inherited are stored at upper level to enable early pruning of a large search space. At the element level,the path repository preserves detailed child-parent links so as to access quickly the parent and improve greatly the query processing efficiency. The group-based element reference is used instead of global IDs to enable the heterogeneous XML values to be differentiated according to their groups with similar element values clustered and indexed.