关键词: XML，前缀编码，分层结构，子树

Abstract: Most of the XML query strategies are based on some prefix schemes[1-4].By analyzing the current prefix schemes,we proposed a novel prefix encoding scheme with layered structure. The new prefix encoding scheme has relatively smaller mean coding length, and the code length is not increased with the depth increment of XML document. Another advantage this scheme brings out is, the query process was accelerated because component code comparisons for Xpath query axis computation become fewer with smaller code length. Extensive theoretic analysis and experimental resups show that this scheme is a better one which accelerates query process and saves the store space for the codes.

Key words: XML, Prefix encoding, Layered structure, Subtree