Data Mining Interview Questions and Answers

 

What is data warehousing?

"In computing, a data warehouse (DW) is a database used for reporting and analysis.
The data stored in the warehouse is uploaded from the operational systems. The data
may pass through an operational data store for additional operations before it is
used in the DW for reporting.



A data warehouse maintains its functions in three layers: staging, integration,
and access. Staging is used to store raw data for use by developers. The integration
layer is used to integrate data and to have a level of abstraction from users. The
access layer is for getting data out for users.



The term Data Warehouse was coined by Bill Inmon in 1990, which he defined in the
following way: "A warehouse is a subject-oriented, integrated, time-variant
and non-volatile collection of data in support of management's decision making
process". He defined the terms in the sentence as follows:



Subject Oriented:




Data that gives information about a particular subject instead of about a company's
ongoing operations.



Integrated:




Data that is gathered into the data warehouse from a variety of sources and merged
into a coherent whole.



Time-variant:




All data in the data warehouse is identified with a particular time period.



Non-volatile:




Data is stable in a data warehouse. More data is added but data is never removed.
In computing, a data warehouse (DW) is a database used for reporting and analysis.
The data stored in the warehouse is uploaded from the operational systems. The data
may pass through an operational data store for additional operations before it is
used in the DW for reporting.



A data warehouse maintains its functions in three layers: staging, integration,
and access. Staging is used to store raw data for use by developers. The integration
layer is used to integrate data and to have a level of abstraction from users. The
access layer is for getting data out for users.



The term Data Warehouse was coined by Bill Inmon in 1990, which he defined in the
following way: "A warehouse is a subject-oriented, integrated, time-variant
and non-volatile collection of data in support of management's decision making
process". He defined the terms in the sentence as follows:



Subject Oriented:




Data that gives information about a particular subject instead of about a company's
ongoing operations.



Integrated:




Data that is gathered into the data warehouse from a variety of sources and merged
into a coherent whole.



Time-variant:




All data in the data warehouse is identified with a particular time period.



Non-volatile:




Data is stable in a data warehouse. More data is added but data is never removed.
This enables management to gain a consistent picture of the business. "

Posted by:Richards