Diseño fisico 1

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Diseño fisico

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Diseño fisico 1

  1. 1. DATA WAREHOUSINGPhysical Design
  2. 2. 2
  3. 3.  Logical database design  What are the facts and dimensions?  Goals: Simplicity, Expressiveness  Make the database easy to understand  Make queries easy to ask
  4. 4.  Physical database design  How should the data be arranged on disk?  Goal: Performance ▪ Manageability is an important secondary concern  Make queries run fast
  5. 5.  Trade-off between query performance and load performance
  6. 6.  To make queries run fast:  Precompute as much as possible  Build lots of data structures ▪ Partitions ▪ Materialized views ▪ Indexes
  7. 7.  But…  Data structures require disk space to store  Building/updating data structures takes time  More data structures → longer load time
  8. 8.  Base data  Fact tables and dimension tables  Fact table space >> Dimension table space Indexes  100%-200% of base data Aggregates / Materialized Views  100% of base data Extra data structures 2-3 times size of base data
  9. 9.  The Data Warehouse Toolkit.Second Edition.The Complete Guide to Dimensional Modeling.Ralph Kimball.Margy Ross

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