Data warehousing is the segregation of operations data into manageable units that are all related to one another.
In a data warehouse, only portions of a business’s overall data will be included. Aggregate data will be reported in a sequential manner and, once placed within the database, will never be altered. Additional information may be added, but original data will not be changed.
The purpose of a data warehouse is to make timely information available to decision makers in order that they can make informed decisions based on accurate current information.
A data warehouse should be organized by related data, sequential in nature to show changes in data over time, (permanent) unable to be overwritten or destroyed, and integrated with the company’s main computer in some way.
The difference in a data warehouse and a hard drive is that data warehouse information is sorted in a way to make reporting fast, efficient and accurate.
Data warehouses have evolved over time from simple systems that were merely duplicates of the main operating system that could be used while data operations were occurring on the main system.
Some businesses update the data in their data warehouse according to a preset time schedule. Updates can be performed monthly, weekly, or daily. Other systems update the data warehouse on a transaction by transaction basis.