Persistence in Enterprise Data Warehouses

Yet, persistence of redundant data in Data Warehouses is often simply justified with an achievement of better performance when accessing data for analysis and reporting. Especially in Enterprise Data Warehouse systems, data management via multiple persistence levels is necessary to condition the huge amount of data into an adequate format for its final usage. However, there are further reasons to store data persistently, which are often not recognized when designing such warehouses. As processing and maintenance of data is complex and requires huge effort, less redundancy will downsize effort. Latest in-memory technologies enable good response times for data access, so that the question arises, what data for what purposes really need to be stored persistently and how can this be efficiently decided. We present a compendium of purposes for data persistence and use it as a basis for decisionmaking whether to store data or not. As an outlook, we expand this discussion on Enterprise Data Warehouses based on in-memory databases.