What is Data Warehousing?

Data warehousing combines data from multiple, usually varied, sources into one comprehensive and easily manipulated database. Different methods can then be used by a company or organization to access this data for a wide range of purposes. Analysis can be performed to determine trends over time and to create plans based on this information. Smaller companies often use more limited formats to analyze more precise or smaller data sets, though warehousing can also utilize these methods.

Common methods for accessing systems of data warehousing include queries, reporting, and analysis. Because warehousing creates one database, the number of sources can be nearly limitless, provided the system can handle the volume. The final result, however, is homogeneous data, which can be more easily manipulated. System queries are used to gain information from a warehouse and this creates a report for analysis.

Companies commonly use data warehousing to analyze trends over time. They might use it to view day-to-day operations, but its primary function is often strategic planning based on long-term data overviews. From such reports, companies make business models, forecasts, and other projections. Routinely, because the data stored in data warehouses is intended to provide more overview-like reporting, the data is read-only.

This does not mean that data warehousing involves information that is never updated. On the contrary, the data stored in warehouses is updated all the time. It is the reporting and the analysis that take more of a long-term view.

Data warehousing is not always the best method for storing all of a company's data. Companies often use it to house the necessary information for specific analysis. More comprehensive data storage requires different capacities that are more static and less easily manipulated than those used for warehousing. This can include internal servers or data storage terminals meant to be accessed and used by various individuals within a business.

While larger companies typically use data warehousing to analyze big sets of information for enterprise purposes, smaller companies wishing to review just one subject often utilize "data marts." These are much more specific and targeted in their storage and reporting. Data warehousing can include smaller amounts of data grouped into "marts," which are then connected together as part of the larger system. In this way, a major company might use both warehousing and data marts, letting users choose the best source and functionality depending on their current needs.