title: Why do we need Data Warehouse?
body: <p>I was wondering about why and when we need a data warehouse, I mean the main goal of data warehouse is to provide a reporting from multidimentional view, but in some case there is a way to build a report using DBMS, it can produce a report from multidimentional view, about the size of the database, the size can be made incrementally, and about integration DBMS also can make integration from many data source and if they have a different key from many data source, dbms can fix it (althought we're not using data warehouse), from the peformance side, how much time it will take to generate a report from operational data store and generate a report from a data warehouse, are the processing time is having a big gap?</p>
  
  <p>Sorry for bad english and weird question, I'm still learning about data warehouse.</p>