Theory and Practices in Xml Query Optimization

Abstract

As computers and technology continue to become more commonplace and essential to everyday life, more data is captured, stored, and analyzed by a variety of institutions. As this amount of data grows, so does the need for efficient methodologies and tools used to store, retrieve, and transform the data. A common method used to store this schemaless, semi-structured data is through the Extensible Markup Language, XML. In this way, an XML document is viewed as a database. With this sizable amount of data stored in a common format, one problem is how to efficiently query XML documents. While relational database management systems contain built-in query optimizers, no such framework exists for XML databases. A multitude of document shapes, query shapes, index structures, and query techniques exist for XML databases, but the implications of these choices and their effects on query processing have not been investigated in a common framework. This paper focuses on the theory and practices applied to solve the problem of query optimization in XML databases.

Keywords: Query Optimization, XML Databases, Cost Model, Query Optimization issues.