Matthias Nicola

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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)
XML parsing is generally known to have poor performance characteristics relative to transactional database processing. Yet, its potentially fatal impact on overall database performance is being underestimated. We report real-word database applications where XML parsing performance is a key obstacle to a successful XML deployment. There is a considerable(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)
K. Beyer R. Cochrane M. Hvizdos V. Josifovski J. Kleewein G. Lapis G. Lohman R. Lyle M. Nicola F. Özcan H. Pirahesh N. Seemann A. Singh T. Truong R. C. Van der Linden B. Vickery C. Zhang G. Zhang Comprehensive and efficient support for XML data management is a rapidly increasing requirement for database systems. To address this requirement, DB2 Universal(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)
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)