Data WarehousesTopicsWhat Is A Data Warehouse?HistorySlide 5Slide 6Data Warehouse CharacteristicsSlide 8Operational Database vs. Data WarehouseSlide 10Slide 11ArchitectureSlide 13ReferencesPatrick Seto CS157A Section 3Data WarehousesPresented by Patrick SetoCS157A Section 3Patrick Seto CS157A Section 3TopicsWhat Is A Data Warehouse?HistoryCharacteristicsOperational Database vs. Data WarehouseArchitecturePatrick Seto CS157A Section 3What Is A Data Warehouse?The term "data warehouse" refers to a special type of database that acts as the central repository for company data. It can be thought of as a database archive that is segregated from the operational databases, and used primarily for reporting and data mining purposes.Patrick Seto CS157A Section 3HistoryData warehouses were first developed in the 1980s in response to the growing demand for management information analysis, which operational databases could not perform without drastically affecting response time.Patrick Seto CS157A Section 3HistoryOff line Operational DatabasesData warehouses in this initial stage are exact copies of operational databases that have been copied to off-line servers where the processing load of reporting does not impact on the operational system's performance.Off line Data WarehouseData warehouses in this stage of evolution are updated regularly at a specified time interval (e.g., daily, weekly, monthly, etc.) from the operational systems, and the data is stored in an integrated reporting-oriented data structure.Patrick Seto CS157A Section 3HistoryReal Time Data WarehouseData warehouses at this stage are updated each time an operational system performs a transaction.Integrated Data WarehouseData warehouses at this stage are used to generate activity or transactions that are passed back into the operational systems for use in the daily activity of the organization.Patrick Seto CS157A Section 3Data Warehouse CharacteristicsSubject-orientedThe data in the database is organized so that all the data elements relating to the same real-world event or object are linked together.Time-variantThe changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time.Patrick Seto CS157A Section 3Data Warehouse CharacteristicsNon-volatileData in the database is never over-written or deleted. Once committed, the data is static, read-only, but retained for future reporting.IntegratedThe database contains data from most or all of an organization's operational applications, and that this data is made consistent.Patrick Seto CS157A Section 3Operational Database vs. Data WarehouseThe processing load of reporting reduced the response time of the operational systems.The database designs of operational systems were not optimized for information analysis and reporting.Patrick Seto CS157A Section 3Operational Database vs. Data WarehouseMost organizations had more than one operational system, so company-wide reporting could not be supported from a single system.Development of reports in operational systems often required writing specific computer programs which was slow and expensive.Patrick Seto CS157A Section 3Operational Database vs. Data WarehouseConsolidation of data from a wide variety of data sources.Ability to analyze data beyond the level of standard monitoring reports.Operational response time unaffected.Patrick Seto CS157A Section 3ArchitecturePatrick Seto CS157A Section 3ArchitecturePatrick Seto CS157A Section
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