1. Describe the roles and purpose of data warehouses and data marts in an organization.
The purpose of the Data Warehouse in the overall Data Warehousing Architecture is to integrate corporate data. It contains the "single version of truth" for the organization that has been carefully constructed from data stored in disparate internal and external operational databases.
The amount of data in the Data Warehouse is massive. Data is stored
at a very granular level of detail. For example, every "sale" that has
ever occurred in the organization is recorded and related to dimensions
of interest. This allows data to be sliced and diced, summed and
grouped in unimaginable ways.
Contrary to popular opinion, the Data Warehouses does not contain
all the data in the organization. It's purpose is to provide key
business metrics that are needed by the organization for strategic and
tactical decision making. Decision makers don't access the Data
Warehouse directly. This is done through various front-end Data
Warehouse Tools that read data from subject specific Data Marts. The
Data Warehouse can be either "relational" or "dimensional". This
depends on how the business intends to use the information.
2. Explain the relationship between business intelligence (BI) and a data warehouse (DW).
BI is a business management term that refers to the applications and
technologies used to gather, provide access to, and analyses data and
information about a company's operations. A DW is a repository for a
company's historical data. DW can be physical or virtual, and they can
be structurally relational, quasi-relational, summarized, cubes, flat
files, or a combination of styles. DW is the set of technologies and
techniques that you use to build and manage the data warehouse.
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