... conventions, measurements, encoding structures, and physical attributes, even when the underlying operational systems store the data differently; * Non-volatile means the data warehouse is read-only: data is loaded into the data warehouse and accessed there; * Time-variant data represents long-term data--from five to ten years as opposed to the 30 to 60 days time periods of operational data. Data warehousing is a concept. It is a set of hardware and software components that can be used to better analyze the massive amounts of data that companies are accumulating to make better business decisions. Data Warehousing is not just data in the data warehouse, but also the architecture and tools to collect, query, analyze and present information. 1.2. Concepts 1.2.1. Operational / informational data: Operational data is the data you use to run your business. This data is what is typically stored, retrieved, and updated by your Online Transactional Processing (OLTP) system. An OLTP ...

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