...MODERN DATABASE MANAGEMENT / JfFFREY A. HOFFER . Warehousing Success 426 Data Warehouse Architectures 428 Generic Two-Level Architecture 428 Independent Data Mart Data Warehousing Environment 426 429 C O NTENTS Dependent Data Mart and Operational Data Store Architecture: A Three-Level Approach Logical Data Mart and Real-Time Data Warehouse Architecture 432 Three-Layer Data Architecture 435 Role of the Enterprise Data Model 435 Role of Metadata 436 Some Characteristics of Data Warehouse Data Status Versus Event Data 437 Transient Versus Periodic Data 438 An Example of Transient and Periodic Data 438 Transient Data 438 Periodic Data 439 Other Data VVarehouse Changes 440 The Reconciled Data Layer 441 Characteristics of Data after ETL 441 The ETL Process 442 Extract 442 Cleanse 444 Load and Index 446 Data Transformation 447 Data Transformation Functions 448 Record-Level Functions 448 Field-Level Functions 449 More Complex Transformations 451 Tools to Support Data Reconciliation 451 Data Quality Tools 451 Data Conversion Tools 452 Data Cleansing Tools 452 Selecting Tools 452 The Derived Data Layer 452 Characteristics of Derived Data 452 The Star Schema 453 Fact Tables and Dimension Tables 453 Example Star Schema 454 Surrogate Key 455 Grain of Fact Table 456 Duration of the Database 456 Size of the Fact Table 457 Modeling Date and Time 458 Variations of the Star Schema 458 Multiple Fact Tables 458 Factless Fact Tables...
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