Short  Questions Answers 

Q What is difference between datawarehouse and datawarehousing ?
A Datawarehouse is physical space where historical data is stored where as the process of storing this data in database is called datawarehousing.


Q What are the characteristics of datawarehouse?

  • Subject- Oriented - should be related to a subject eg sales ,marketting
  • Integrated- should be intehrated from various sorces after removing inconsistencies
  • Non VolatileNonvolatile means that, once entered into the warehouse, data should not change
  • Time VariantAll data in the data warehouse is identified with a particular time period.

Q What is  Enterprise Data warehouse
A  It collects all information about subjects (customers,products,sales,assets, personnel) that span the entire organization

Q What is Data Mart
A Departmental subsets that focus on selected subjects eg. sales data mart , hr data mart , marketting data mart etc.

Q What is Decision Support System (DSS) ?
A  It is an Information technology to help the knowledge worker (executive, manager, analyst) make faster & better decisions.


Q What is difference between OLTP and datawarehouse ?

A  OLTP is  

  • Application Oriented
  • Used to run business
  • Detailed data
  • Current up to date
  • Isolated Data
  • Repetitive access
  • Clerical User


  • Subject Oriented
  • Used to analyze business
  • Summarized and refined
  • Snapshot data
  • Integrated Data
  • Ad-hoc access
  • Knowledge User (Manager)
Q What is difference between ROLAP, MOLAP and HOLAP ?
A  Relational OLAP (ROLAP)
–Relational and specialized relational DBMS to store and manage warehouse data
–OLAP middleware to support missing pieces
   Multidimensional OLAP (MOLAP)
–Array-based storage structures
–Direct access to array data structures
   Hybrid OLAP (HOLAP)
–Storing detailed data in RDBMS
–Storing aggregated data in MDBMS
–User access via MOLAP tools