CONSISTENCY ALGORITHMS FOR MULTISOURCE WAREHOUSE VIEW MAINTENANCE

A warehouse is a data repository containing integrated information for efficient querying and analysis. Maintaining the consistency of wareh ouse data is challenging, especially if the data sources are autonomou s and views of the data at the warehouse span multiple sources. Transa ctions containing multiple updates at one or more sources, e.g., batch updates, complicate the consistency problem. In this paper we identif y and discuss three fundamental transaction processing scenarios for d ata warehousing. We define four levels of consistency for warehouse da ta and present a new family of algorithms, the Strobe family, that mai ntain consistency as the warehouse is updated, under the various wareh ousing scenarios. All of the algorithms are incremental and can handle a continuous and overlapping stream of updates from the sources. Our implementation shows that the algorithms are practical and realistic c hoices for a wide variety of update scenarios.