Showing papers by "Zhiyuan Chen published in 2004"

Transformation tool for mapping XML to relational database

Abstract: An XML transformation tool that constructs a relational database with associated physical structures that can be populated with shredded XML data. A mapping transformation enumerator examines queries in the workload and enumerates mapping transformations that use XSD specific constraints and statistics on XML data and can be used to generate mappings from XSD to relational database schema that may lead to better performance in presence of physical design. A design tuner that searches mappings generated from a default mapping using enumerated transformations together with physical design structures associated with those mappings and selects a preferred mapping and the physical design structures. Cost estimates for performing queries in the workload are determined for the relational database implementing the mapping and associated physical design structures.

Method for matching XML twigs using index structures and relational query processors

Abstract: A framework defining a family of index structures useful in evaluating XML path expressions (i.e., twigs) in XML database is disclosed. Within this framework, two particular index structures with different space-time tradeoffs are presented that prove effective for the evaluation of twigs with value conditions. These index structures can be realized using access methods of an underlying relational database system. Experimental results show that the indices disclosed achieve significant improvement in performance for evaluating twig queries as compared with previously proposed XML path indices.

Storing XML (with XSD) in SQL databases: interplay of logical and physical designs

Abstract: In this paper, we examine the interplay of logical and physical design, and experimentally demonstrate that: (1) solving the logical mapping and the physical design problem independently leads to a suboptimal solution; (2) taking into account the physical design space impacts the space of logical mapping. Specifically, well-known outlining and inlining mapping options are rendered unnecessary because they are functionally subsumed by two physical design options: indexes and vertical partitioning. We propose a search algorithm that judiciously explores the extreme large combined space of logical and physical design. The algorithm only searches the XSD-specific logical design options and uses heuristics to further prune the search space. We experimentally compare the quality (in terms of the time to execute the query workload on resulting design) and efficiency (in terms of the search time) of our algorithm with known algorithms as well as a default XSD based mapping and an Edge-Table Mapping that does not use XSD on both real and synthetic data.