- Before
starting learning Data Warehouse, we should be aware of the Father of Data
Warehouse, So Ralph Kimball
and Bill
Inmon are known as Father of Data Warehouse. - Ralph
Kimball, is a proponent of an approach frequently considered as bottom-up
,to data warehouse design. In the so-called bottom-up approach data marts
are first created to provide reporting and analytical capabilities for
specific business processes. Data marts contain atomic data and, if
necessary, summarized data. These data marts can eventually be unioned
together to create a comprehensive data warehouse. The combination of data
marts is managed through the implementation of what Kimball calls “a
data warehouse bus architecture. - Business
value can be returned as quickly as the first data marts can be created. Maintaining tight management over the data warehouse bus
architecture is fundamental to maintaining the integrity of the data
warehouse.
- Bill
Inmon, one of the first authors on the subject of data warehousing, has
defined a data warehouse as a centralized repository for the entire
enterprise. Inmon is one of the leading proponents of the top-down
approach to data warehouse design, in which the data warehouse is designed
using a normalized enterprise data model. “Atomic” data, that
is, data at the lowest level of detail, are stored in the data warehouse.
In the Inmon vision the data warehouse is at the center of the
“Corporate Information Factory” (CIF), which provides a logical
framework for delivering business intelligence (BI) and business
management capabilities. The CIF is driven by data provided from business
operations.
Inmon states that the
data warehouse is:
data warehouse is:
- Subject-oriented
–
The data in the data warehouse is
organized so that all the data elements relating to the same real-world event
or object are linked together.
The data in the data warehouse is
organized so that all the data elements relating to the same real-world event
or object are linked together.
- Time-variant
–
The changes to the data in the data
warehouse are tracked and recorded so that reports can be produced showing
changes over time.
The changes to the data in the data
warehouse are tracked and recorded so that reports can be produced showing
changes over time.
- Non-volatile
– Data in the data
warehouse is never over-written or deleted – once committed, the data is
static, read-only, and retained for future reporting.
warehouse is never over-written or deleted – once committed, the data is
static, read-only, and retained for future reporting.
- Integrated
– The data warehouse
contains data from most or all of an organization’s operational systems and
this data is made consistent.
contains data from most or all of an organization’s operational systems and
this data is made consistent.