Characteristics of Data Warehouse:
A common way of introducing data warehousing is to refer to the
characteristics of a data warehouse as set forth by William Inmon:
Subject Oriented
Integrated
Non Volatile
Time Variant
Subject Oriented :
The ability to define a data warehouse by subject manner.
For ex: To learn more about your company's sales data, you can build a warehouse
that concentrates on sales. Using this warehouse, you can answer
questions like "Who was our best customer for this item last year?" This
ability to define a data warehouse by subject matter, sales in this
case, makes the data warehouse subject oriented.
Integrated :
Integration is closely related to subject orientation. Data warehouses must keep the data from different sources into a consistent format.They must resolve such problems as naming conflicts and inconsistencies
among units of measure. When they achieve this, they are said to be
integrated.
Non Volatile :
It means, Data, once it entered into the data warehouse, it should not be changed. This is logical because the purpose of a warehouse is to enable you to analyze what has occurred.
Time Variant :
In order to discover trends in business, analysts need large amounts of data. This is very much in contrast to OLTP systems, where performance requirements demand that historical data be
moved to an archive. A data warehouse's focus on change over time is
what is meant by the term time variant.
