Database Reference
In-Depth Information
6.
Accessibility:
The data warehouse is a predominantly
read-only database, with periodic batch updates from the
operational databases that are connected to it. It does not
support on-line interactive updates.
7.
Life Cycle:
The data warehouse development life cycle differs
from classical approach to database development in that
whereas the data warehouse development is data-driven, the
classical database approach tends to be process-driven.
8.
Levels of Detail:
In a typical data warehouse, there may be
several levels of detail. These include current detail, old detail,
lightly summarized data, and highly summarized data.
9.
Data Set:
The data warehouse is characterized by read-only
transactions on very large data sets. This is in contrast to the
operational database, which is characterized by numerous
update transactions on a more narrowly defined data set.
10.
Relevance:
The data warehouse environment has a system
that keeps track of all data sources, transformations and
storage. This is essential if the data warehouse is to maintain
its relevance.
11.
Metadata:
The data warehouse's metadata forms a critical
component of its environment. The metadata provides the
following functions: definitions of data elements in the
warehouse; identification of data source, transformation,
integration, storage, usage, relationships, and history of each
data element.
12.
Resource Usage:
The data warehouse typically enforces
optimal usage of the data by enforcing some form of
chargeback mechanism for resource usage.
24.4 Data Warehouse Architecture
The architecture of a data warehouse varies depending upon the specifics of an
organization's situation. Three common architectures have been identified:
•
Basic Data Warehouse
•
Data Warehouse With a Staging Area
•
Data Warehouse With Staging Area and Data Marts
24.4.1 Basic Data Warehouse Architecture
Figure
24-3
shows a simple architecture for a data warehouse. End users directly access
data derived from several source systems through the data warehouse.
