Data storage practices and query processing in XML databases: A survey

With the rapid emergence of XML as a data exchange standard over the Web, storing and querying XML data have become critical issues. The two main approaches to storing XML data are (1) to employ traditional storage such as relational database, object-oriented database and so on, and (2) to create an XML-specific native storage. The storage representation affects the efficiency of query processing. In this paper, firstly, we review the two approaches for storing XML data. Secondly, we review various query optimization techniques such as indexing, labeling and join algorithms to enhance query processing in both approaches. Next, we suggest an indexing classification scheme and discuss some of the current trends in indexing methods, which indicate a clear shift towards hybrid indexing.

► We review the two main approaches for storing XML data.
► We review the query optimization techniques to enhance query processing in both storage methods.
► We suggest an indexing classification scheme.
► We discuss the current trends, which indicate a clear shift towards hybrid indexing.
► We highlight some open and challenging issues that need to be address.