Database Reference
In-Depth Information
Data Marts
The easiest way to conceptually view a data mart is that a mart needs
to be an extension of the data warehouse. Data is integrated as it
enters the data warehouse from multiple legacy sources. Data marts
then derive their data from the central data warehouse source. The
theory is that no matter how many data marts are created, all the data
is drawn from the one and only version of the truth, which is the data
contained in the warehouse. Distribution of the data from the ware-
house to the mart provides the opportunity to build new summaries
to fit a particular department's need. The data marts contain subject-
specific information supporting the requirements of the end users in
individual business units. Data marts can provide rapid response to
end-user requests if most queries are directed to precomputed, aggre-
gated data stored in the data mart.
Extract Transform Load
Data Extraction-Transformation-Load (ETL) tools are used to extract
data from data sources, cleanse the data, perform data transforma-
tions, and load the target data warehouse and then again to load the
data marts. The ETL tool is also used to generate and maintain a central
metadata repository and support data warehouse administration. The
more robust ETL tools integrate with OLAP tools, data-modeling tools,
and data-cleansing tools at the metadata level. Appendix 10 (available on
the CRC Press website for download at http://www.crcpress.com/prod-
uct/isbn/9781482249941) provides a good set of checklists for selecting
and integrating a metadata repository.
Business Intelligence (BI)
BI provides the tools required by users to specify queries, create arbi-
trary reports, and analyze their own data using drill-down and OLAP
functions. Putting this functionality in the hands of the power users
allows them to ask their own questions and gives them quick and easy
access to the information they need. However, one tool does not fit all.
The BI tools arena still requires that we match the right tools to the right
end user.
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