Logical design of data warehouses from XML

Abstract

Data warehouse is a database that collects and integrates data from heterogeneous sources in order to support a decision making process. Data exchanged over the Internet and intranets has recently become an important data source, having XML as a standard format for exchange. The possibility of integrating available XML data into data warehouses plays an important role in providing enterprise managers with up-to-date and relevant information about their business domain. We have developed a methodology for data warehouse design from the source XML Schemas and conforming XML documents. As XML data is semi-structured, data warehouse design from XML brings many particular challenges. In this paper the final steps of deriving a conceptual multidimensional scheme are described, followed by the logical design, where a set of tables is created according to the derived conceptual scheme. A prototype tool has been developed to test and verify the proposed methodology. Data warehousing system is a set of technologies and tools that enable decision-makers (managers and analysts) to acquire, integrate and flexibly analyze information coming from different sources. The central part of the system is a large database specialized for complex analysis of historical data, called a data warehouse. The process of building a data warehousing system includes analysis of the data sources, design of a warehouse model that can successfully integrate them and later the construction of the warehouse according to the proposed model. Decision-makers use OLAP (OnLine Analytical Processing) tools to put queries against the warehouse in a quick, intuitive and interactive way. OLAP tools use the multidimensional data model, which enables focusing on small pieces of data, generally a few numerical parameters, that are most interesting for the decision making process. Other data in the warehouse are organized hierarchically into several independent groups, called dimensions, and used to perform calculations with the few important parameters. Data warehouses, owned by big enterprises and organizations, integrate data from heterogeneous sources: relational databases or other legacy database models, semi-structured data and different file formats. Recently, the World Wide Web, Web services and different information systems for exchanging data over the Internet and private networks have become an important data source.