Characteristics of the Data Warehouse

The Data Warehouse is a database that provides support for decision making.

In simple terms, a data warehouse (DW) is a pool of data produced to support decision making; it is also a repository of current and historical data of potential interest to managers throughout the org.

Integrated

• Integration is closely related to subject orientation. Data warehouses must place data from from different sources into a consistent format. To do so they must deal with naming conflicts and discrepancies among units of measure. A data warehouse is assumed to be totally integrated.

Subject-Oriented

• Data are organised by detailed subject such as sales, products or customers, containing only information relevant for decision support. Enables users to determin not only how the business is performing but why. differs from an operation database in that most operationAL databases have a product orientation and are tuned to handle transactions that update the database. Comprehensive view of the organisation.

Time Variant (time series) (built-in time aspects)

• Maintains historical data. Does not necessarily provide current status (except in real time systems). They detect trends, deviations long-term relationships for forecating and comparrisons, leading to decision making. There is a temporal quality to every data warehouse. Time is the one important dimension that all data warehouses must support. Data for analysis from multiple sources contain multiple time points (daily, weekly, monthly).

Non-Volatile (can't be changed)

• After data are enetered into a data warehouse, users cannot change or update the data. Obsolete data are discarded, and changes are recorded as new data. Enables the data warehouse to be tuned almost exclusively for data access.

Summarized
Not normalized
Sources
Metadata (Data about data)