IGI Global is prohibited. Chapter II Dynamic Workload for Schema Evolution in Data Warehouses: a Performance Issue

A data warehouse allows the integration of heterogeneous data sources for identified analysis purposes. The data warehouse schema is designed according to the available data sources and the users ' analysis requirements. In order to provide an answer to new individual analysis needs, we previously proposed, in recent work, a solution for on-line analysis personalization. We based our solution on a user-driven approach for data warehouse schema evolution which consists in creating new hierarchy levels in OLAP (On-Line Analytical Processing) dimensions. One of the main objectives of OLAP, as the meaning of the acronym refers, is the performance during the analysis process. Since data warehouses contain a large volume of data, answering decision queries efficiently requires particular access methods. The main issue is to use redundant optimization structures such as views and indices. This implies to select an appropriate set of materialized views and indices, which minimizes total query response time, given a limited storage space. A judicious choice in this selection must be cost-driven and based on a workload which represents a set of users ' queries on the data warehouse. In this chapter, we address the issues related to the workload’s evolution and maintenance in data warehouse systems in response to new requirements modeling resulting from users ’ personalized analysi