Abstract: Structure join operation is the main solution to native XML database query.Structure join operation depends on XML documents’ coding，in order to quickly determinate ancestor-descendant relationships between the nodes of the XML document tree.In this paper，a new coding scheme is proposed，which is named as prefix division （PDIV） coding scheme.The scheme is easy to realize and only one positive integer is needed to express the position of the node in XML tree.The scheme may identify the ancestor-descendant relationships in constant time-bounding.It also supports XML document update.In the scheme，the length of the code is short and it is about o（ln（n））.

Key words: Native XML database, coding scheme, XML query

摘要： Native XML数据库快速查询的实现，可以采用基于XML文档编码的结构连接算法。而结构连接算法的实现需要对XML文档进行编码，以便于快速判断XML文档树结点之间的祖先后裔关系。在对现有编码机制进行综述的前提下，提出一种新的XML文档编码机制——前缀整除编码（PDIV）机制。该机制编码形式简单，只需要一个正整数即可充分表示结点在XML文档树中的位置信息；可以实现祖先后裔关系的快速查询；支持XML文档的更新操作；编码长度较短，编码长度约为o（ln（n））。

关键词: Native XML数据库, 编码机制, XML查询