Query Decomposition Using the XML Declarative Description Language

Thuy, Le Thi Thu; Duong, Doan Dai

doi:10.1007/11424826_114

Cited by 8 publications

(6 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thuy [8] and Ling [5] present decomposition of XML queries, but they miss a problem of balancing between the amount of processing at remote site and at central site, which is solved in this work.…”

Section: Previous Workmentioning

confidence: 94%

Query Decomposition Strategy for Integration of Semistructured Data

Handoko

Getta

2014

Proceedings of the 16th International Conference on Information Integration and Web-Based Applications &Amp; Services

View full text Add to dashboard Cite

Data integration systems provide a unified view of various sources of data distributed over the wide-area networks. User requests issued at a central site must be decomposed into a number of sub-requests, that are later on processed at the remote sites. The results are integrated at a central site and returned to a user.A decomposition strategy of global user requests and scheduling of sub-requests at a central site has a significant impact on performance of data integration process. This paper proposes an efficient decomposition strategy for the systems that integrate semistructured data. We define a new system of operations on XML documents to represent XQuery user requests and the results of decompositions of such requests. A cost-based optimisation is used to find the optimal size of sub-requests and their optimal scheduling at a central site.

show abstract

Section: Previous Workmentioning

confidence: 94%

Query Decomposition Strategy for Integration of Semistructured Data

Handoko

Getta

2014

Proceedings of the 16th International Conference on Information Integration and Web-Based Applications &Amp; Services

View full text Add to dashboard Cite

show abstract

“…Each mapping is modeled by a non-ground XML expression. It describes a correspondence between an object in the integrated schema and its corresponding objects in the local schemas by using two XML sub-expressions [8]. Fig.…”

Section: • Mappingmentioning

confidence: 99%

“…In our approach, a global XML query modeled by XDD can be simultaneously decomposed into n sub-queries conforming to specific structures of local sources [8]. For instance, in Fig.…”

Section: ) Query Decomposition Componentmentioning

confidence: 99%

A Unified Framework for the Semantic Integration of XML Databases

Duong

Thuy

2007

2006 1st International Conference on Digital Information Management

Self Cite

View full text Add to dashboard Cite

This paper proposes an XML Declarative Description (XDD)-based integration framework for XML databases. All data components and processing components of the framework, such as databases, ontologies, queries and schema integration components can be formulated by XDD. Since the boundary between the system's components is removed, the interoperation capacity between them is enhanced, thus reducing the overhead of the system's communication. Moreover, an important achievement of this framework is that it can integrate n schemas at a time and simultaneously decompose a query into n subqueries.

show abstract

“…In Global-As-View (GAV) integration systems [5,11,12], all participating data sources follow their own schemas, which typically differ from the global schema. When users pose queries based on this global schema, these queries cannot be directly employed to query local sources due to the different structures of the global schema and the local ones.…”

Section: Introductionmentioning

confidence: 99%

“…The common feature of these systems is that a global view (i.e., a global schema) is built to reconcile discrepancies among heterogeneous data sources. Based on this global view, a set of mappings [11,13] is defined to describe the correspondences of elements between local sources and those of the global view. A mediator [5], the main component of such a system, handles query processing using mappings.…”

Section: Introductionmentioning

confidence: 99%

A Bottom-up Strategy for Query Decomposition

Thuy

Duong

Bhavsar

et al. 2007

2006 1st International Conference on Digital Information Management

Self Cite

View full text Add to dashboard Cite

In order to access data from various different data repositories, in Global-As-View approaches an input query is decomposed into several subqueries. Normally, this decomposition is based on a set of mappings, which describe the correspondence of data elements between a global schema and local ones. However, building mappings is a difficult task, especially when the number of participating local schemas is large. In our approach, an input query is automatically decomposed into subqueries without using mappings. An algorithm is proposed to transform a global path expression (e.g., an XPath query) into local path expressions (e.g. , XPath queries) executable in local schemas. This algorithm transforms parts of a path expression from right to left. This transformation is applied from the bottom to the top of a tree and depends on structures of local schemas. Compared to topdown approaches as by Lausen and Marron (LM), ourbottom-up approach can be more efficient. Even in the worst case, the time complexity of our algorithm can be n times better than that of LM, where n is the number of parts in a global query. In the best case, for a k-ary tree of height h, the time complexity of our algorithm is T(n,k,h)= min(n,h), whereas that of LM we have found is T(n,k,h)=n*(k h+1 -1)/(k-1) This can reduce to a large extent the time for forming subqueries for local (e.g., XML) schemas.

show abstract

Query Decomposition Using the XML Declarative Description Language

Cited by 8 publications

References 5 publications

Query Decomposition Strategy for Integration of Semistructured Data

Query Decomposition Strategy for Integration of Semistructured Data

A Unified Framework for the Semantic Integration of XML Databases

A Bottom-up Strategy for Query Decomposition

Contact Info

Product

Resources

About