Data Warehouse

A data warehouse is a centralized, large-sized repository of databases and data files that allows users to access data, to perform data query functions, or to conduct data analyses. Most data warehouses utilize advanced network technologies and frameworks (such as the Internet and the World Wide Web) to provide flexible access of databases and files. Inmon and Kelly noted that data warehouses should provide a subject-oriented, integrated, time-variant, and nonvolatile collection of data in support of management's decision-making process. The major goal of a data warehouse is to facilitate data archiving, data searching, and data sharing for multiple users. A centralized data warehouse can increase data consistency and decrease the cost of data maintenance.

The implementation of data warehouses is important for many GIS projects and applications. Many federal and local governments in the United States have established various geospatial data warehouses for land use data, transportation data, satellite imagery, and other municipal GIS data sets. The Internet and the Web are now the storage devices or media used for the archiving and delivery of GIS data layers and remotely sensed imagery. The Web-based geospatial data warehouses can allow users to catalog, index, and search these data sets in what are now recognized as digital libraries.