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 Volatile- Nonvolatile means that, once entered into the warehouse, data should not change
Time Variant - All 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
Used to run business
Current up to date
Used to analyze business
Summarized and refined
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