Data Warehouse
Stefano Rizzi · Wiley Encyclopedia of Computer Science and Engineering · 2008
Abstract A data warehousing system is a collection of methods, techniques, and tools that support the knowledge worker (manager, administrator, analyst) in decision making by transforming operational data, stored in corporate databases, into strategic information that can be accessed quickly, reliably, and flexibly. The core idea of data warehousing is to separate the analytical queries that extract strategic information, which are commonly called OLAP (On‐Line Analytical Processing) queries, from the operational ones, called OLTP (On‐Line Transactional Processing) queries, by building a new information repository (the data warehouse) that integrates the elemental data coming from different sources, organizes them into an appropriate structure, and makes them available for analyses and evaluations aimed at planning and decision making. In this article, after providing the basic definition of a data warehouse, we will describe the main architectures of data warehousing systems, define the multidimensional model used to store information in the data warehouse and its implementations, explain the main techniques for accessing information, survey the main issues related to data warehouse design, and mention the main topics of research in this field.