XIST: An XML Index Selection Tool

Abstract

Abstract. XML indices are essential for efficiently processing XML queries which typically have predicates on both structures and values. Since the number of all possible structural and value indices is large even for a small XML document with a simple structure, XML DBMSs must carefully choose which indices to build. In this paper, we propose a tool, called XIST, that can be used by an XML DBMS as an index selection tool. XIST exploits XML structural information, data statistics, and query workload to select the most beneficial indices. XIST employs a technique that organizes paths that are evaluated to the same result into equivalence classes and uses this concept to reduce the number of paths considered as candidates for indexing. XIST selects a set of candidate paths and evaluates the benefit of an index on each candidate path on the basis of performance gains for non-update queries and penalty for update queries. XIST also recognizes that an index on a path can influence the benefit of an index on another path and accounts for such index interactions. We present an experimental evaluation of XIST and current XML index selection techniques, and show that the indices selected by XIST result in greater overall improvements in query response times and often require less disk space.

A methodology for coupling fragments of XPath with structural indexes for XML documents

“…Yi et al [16] developed update techniques for the AðkÞ-index and 1-index. Finally, the integrated use of structural and value indexes has been explored [17], and there have also been investigations on covering indexes [11,12] and index selection [18,19].…”

Schema-conscious XML indexing

“…In practice, only those paths that appear frequently in the query workload need to have indexes built on them. While there has been some recent work on automated XML index selection [31], we do not address this issue here and simply assume that suitable index choices have already been made by the database administrator.…”

“…Finally, the recently proposed XIST index selection tool [31] can be used to identify the set of paths on which SphinX indexes should be constructed.…”

Structural summaries for efficient XML query processing

“…An index selection tool [27] uses algorithms that consider query workload information and cost-benefit formulae to propose both the paths to be included in an index, and also the best index to use for a given query.…”