Path Expression Queries Research Articles

Storing and querying fuzzy XML data in relational databases

Information imprecision and uncertainty exist in many real-world applications and for this reason fuzzy data management has been extensively investigated in various database management systems. Currently, introducing native support for XML data in relational database management systems (RDBMs) has attracted considerable interest with a view to leveraging the powerful and reliable data management services provided by RDBMs. Although there is a rich literature on XML-to-relational storage, none of the existing solutions satisfactorily addresses the problem of storing fuzzy XML data in RDBMs. In this paper, we study the methodology of storing and querying fuzzy XML data in relational databases. In particular, we present an edge-based approach to shred fuzzy XML data into relational data. The unique feature of our approach is that no schema information is required for our data storage. On this basis, we present a generic approach to translate path expression queries into SQL for processing XML queries.

Reasoning about Structural Integrity Constraints for XML

In order to efficiently optimize XML path expression queries,this paper gives a system of structural integrity constraints for XML(XSICs).The pattern system provides effective means to specify the structural relationships between different paths or nodes in form of path implication,path concurrence and path mutual-exclusion,element obligatory inclusion,element exclusive inclusion.On the basis of this,the implication and consistency problems of XSICs are studied.Firstly,the technique of constraint rewriting is introduced to rewrite all kinds of constraints into path constraints.Secondly,a set of inference rules for path implication constraints is developed.Finally,the paper proves the completeness of these inference rules,and gives the consistency determinant method of XSICs by using the path implication closure.

Research of XML regular path expression query based on automaton

Research of XML regular path expression query based on automaton

Query processing strategy of XML path expression based on schema

To make effective use of path information and reduce the number of joint operations,the authors labeled each element or attribute in DTD with a binary prefix code,and introduced the DTD code into the numbering scheme for XML documents. Based on this,path expression queries were decomposed into a series of query fragments. Then these query fragments were efficiently evaluated by using a bit-wise operation of the binary prefix codes. Finally,the results of the query fragments were composed by structural joint. The experimental results show that the proposed approach is effective and efficient.

What makes the differences: benchmarking XML database implementations

XML is emerging as a major standard for representing data on the World Wide Web. Recently, many XML storage models have been proposed to manage XML data. In order to assess an XML database's abilities to deal with XML queries, several benchmarks have also been proposed, including XMark and XMach. However, no reported studies using those benchmarks were found that can provide users with insights on the impacts of a variety of storage models on XML query performance. In this article, we report our first set of results on benchmarking a set of XML database implementations using two XML benchmarks. The selected implementations represent a wide range of approaches, including RDBMS-based systems with document-independent and document-dependent XML-relational schema mapping approaches, and XML native engines based on an Object-Oriented Model and the Document Object Model. Comprehensive experiments were conducted to study relative performance of different approaches and the important issues that affect XML query performance, such as path expression query processing, effectiveness of various partitioning, label-path, and indexing structures.

Performance analysis of parallelization models for path expression queries

In this paper, parallelization models for path expressions queries are studied. Path expression queries involve multiple classes along aggregation/association hierarchies. Parallelization models for path expression queries are “inter-object parallelization” and “inter-class parallelization”. Inter-object parallelization exploits the associativity within complex objects, whereas inter-class parallelization imposes upon process independence. The behaviours of these parallelization models are described in terms of analytical models. Performance evaluation is also performed to confirm the results from the quantitative analysis.

Regular Path Queries with Constraints

The evaluation of path expression queries on semistructured data in a distributed asynchronous environment is considered. The focus is on the use of local information expressed in the form of path constraints in the optimization of path expression queries. In particular, decidability and complexity results on the implication problem for path constraints are established.