1. By Timothy Valihora

2.  IBM Information Server Expert and Information
Management System Expert Timothy Valihora heads
TVMG Consulting. In his role as a data warehousing
and data conversion specialist, Timothy Valihora is
called upon by businesses to provide guidance on
operating systems, server tools, and software
solutions.
Analysts, executives, and corporate decision makers
compile, administrate, and analyze corporate data
using a tool known as a data warehouse. This
complex collection of information and services is
subject oriented and time varying, containing both
operational information and value-added data, such
as history and summaries.

3.  The integration of heterogeneous databases is
typically required to construct a data warehouse, and
two common approaches used are the query-driven
approach and the update-driven approach.
The most efficient and modern approach is the
update-driven approach, where the information from
several heterogeneous sources is copied, processed,
and restructured in advance. This means that an
interface is not required at the local source in order
to query-process. Because the method is an efficient
and high-performance solution, modern data
warehouse systems typically employ the update-
driven approach instead of the query-driven
approach.