Data warehouse

Data warehouse

1. What is data warehouse?

   • physical repository where relational data are specially organized to provide enterprise-wide,cleansed data in standardized format
   • collection of integrated, subject-oriented databases designed to support DSS functions (each unit of data is non-volatile & relevant to some moment in time)

2. Types of DW

   • Enterprise Data Warehouse (EDW)
   • Operational Data Stores (ODS)
   • Data Marts

3. Dimensional Modelling

   • A retrieval-based system that supports high-volume query access
   • 2 types
     • Star Schema
       • Facts & dimensions normally represented by physical tables
       • Fact table contains measures & foregin key for each dimension table (dim table)
     • Snownflake schema