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The major relational database systems have been providing XML support for several years, predominantly by mapping XML to existing concepts such as LOBs or (object-)relational tables. The limitations of these approaches are well known in research and industry. Thus, a forthcoming version of DB2 Universal Database® is enhanced with comprehensive native XML(More)
This paper surveys performance models for distributed and replicated database systems. Over the last 20 years a variety of such performance models have been developed and they differ in (1) which aspects of a real system are or are not captured in the model (e.g. replication, communication, non-uniform data access, etc.) and (2) how these aspects are(More)
Applications in finance and telecommunications (intelligent network, network management, mobile computing) cause renewed interest in distributed and replicated data management. Since synchronous update of replicated data is experienced to degrade distributed systems performance substantially, relaxing the requirement of coherency (mutual consistency) has(More)
In many developing countries there is a tremendous demand for communication and information services, but conventional wired infrastructure to implement them is lacking. Wireless communication is easier and cheaper to introduce and to maintain, especially in remote and less developed areas. Based on the analysis of a distributed health care information(More)
Comprehensive and efficient support for XML data management is a rapidly increasing requirement for database systems. To address this requirement, DB2 Universal Databasee (UDB) now combines relational data management with native XML support. This makes DB2t a truly hybrid database management system with first-class support for both XML and relational data(More)
XQuery and SQL/XML are powerful new languages for querying XML data. However, they contain a number of stumbling blocks that users need to be aware of to get the expected results and performance. For example, certain language features make it hard if not impossible to exploit XML indexes.The major database vendors provide XQuery and SQL/XML support in their(More)
Today,m ore andm ore enterprisesprocess XMLdata, many of them alreadyi nX ML database systems.O nce systems start to grow in size, scalability becomesa ni ssue.O n e of the core operations during insert processingi st h e indexm a intenance.T ypical relationals ystems only have few indexesp e rt able,h owever, XMLd atabase users alreadyl ook at creating(More)
The vast number of design options in replicated databases requires efficient analytical performance evaluations so that the considerable overhead of simulations or measurements can be focused on a few promising options. A review of existing analytical models in terms of their modeling assumptions, replication schemata considered, and network properties(More)