Abstract: Extensible markup language (XML) data has been widely applied in Web data exchange and storage. The research on Twig query processing, which is a core operation for XML query processing, is especially crucial and important. This paper summarizes the development of Twig query processing and optimization on traditional XML data, distributed XML data, uncertain XML data and graph-structured XML data, and analyzes existing problems and challenges. Finally, this paper discusses directions and trends of further research on Twig query processing and optimization.

Key words: Twig query, extensible markup language (XML), distributed XML, uncertain XML, graph-structured XML

摘要： 可扩展标记语言（extensible markup language，XML）数据已被广泛应用于网络数据交换和存储领域。作为XML数据查询的核心操作，Twig查询处理与优化技术具有十分重要的研究意义。为此，全面总结了Twig查询处理与优化技术在传统XML数据、分布式XML数据、不确定XML数据、图模型XML数据中的发展现状，并分析了存在的问题和挑战，最后探讨了Twig查询处理与优化技术今后的发展趋势和研究方向。

关键词: Twig查询, 可扩展标记语言（XML）, 分布式XML数据, 不确定XML数据, 图模型XML数据