Querying XML documents using Prolog engines: When is this a good idea?. Issue 5 (September 2019)

• Record Type: Journal Article
• Authors: Gomes dos Santos, Fábio; Machado, Leonardo; Pinheiro, Rafael; Paes, Aline; Braganholo, Vanessa
• Is Part Of: Information processing & management. Volume 56:Issue 5(2019:Sep.)
• Page Start: 1753
• Page End: 1770
• Publication Date: 2019-09
• Subjects: XML -- XQuery -- Prolog -- Inference -- Query processing; Information storage and retrieval systems -- Periodicals; Information science -- Periodicals; Systèmes d'information -- Périodiques; Sciences de l'information -- Périodiques; Information science; Information storage and retrieval systems; Periodicals; 658.4038
• DOI: 10.1016/j.ipm.2019.05.011
• Languages: English
• ISSNs: 0306-4573

Abstract

Abstract : Highlights: Using Prolog to process XQuery is faster than using native XML tools, for queries that search by key or position on small datasets. For large datasets, or for queries that search for substrings, native XML approaches are the best option. Results show that it is worth investing in an algorithm to automatically translate XQuery into Prolog queries. Abstract: XML has become a universal standard for information exchange over the Web due to features such as simple syntax and extensibility. Processing queries over these documents has been the focus of several research groups. In fact, there is broad literature in efficient XML query processing which explore indexes, fragmentation techniques, etc. However, for answering complex queries, existing approaches mainly analyze information that is explicitly defined in the XML document. A few work investigate the use of Prolog to increase the query possibilities, allowing inference over the data content. This can cause a significant increase in the query possibilities and expressive power, allowing access to non-obvious information. However, this requires translating the XML documents into Prolog facts. But for regular queries (which do not require inference), is this a good alternative? What kind of queries could benefit from the Prolog translation? Can we always use Prolog engines to execute XML queries in an efficient way? There are many questions involved in adopting an alternative approach to run XML queries. In this work, we investigate this matter by translating XML queries into Prolog queries and comparing the query processing times using Prolog and native XML engines. Our work contributes by providing a set of heuristics that helps users to decide when to use Prolog engines to process a given XML query. In summary, our results show that queries that search elements by a key value or by its position (simple search) are more efficient when run in Prolog than in native XML engines. Also, queries over large datasets, or that searches for substrings perform better when run by native XML engines.