Diseño fisico

1. DATA WAREHOUSING
Physical Design

2. 2

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.  Physical database design
 How should the data be arranged on disk?
 Goal: Performance
▪ Manageability is an important secondary concern
 Make queries run fast

5.  Trade-off between query performance and
load performance

6.  To make queries run fast:
 Precompute as much as possible
 Build lots of data structures
▪ Partitions
▪ Materialized views
▪ Indexes

7.  But…
 Data structures require disk space to store
 Building/updating data structures takes
time
 More data structures → longer load time

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.  The Data Warehouse Toolkit.Second Edition.The
Complete Guide to Dimensional Modeling.Ralph
Kimball.Margy Ross