Managing various types of metadata in DWs also has
received a lot of attention resulting in widely accepted industry standard CWM
(OMG, 2003; Vetterli, Vaduva, & Staudt, 2000), supported by major DW software
vendors.
Despite the continuous development in the data warehousing technology that has
lasted fore more than 20 years, it is still a very active area of research. Although
most of the discussed research and technological achievements have been incorporated
into various commercial database/data warehouse management systems, the
discussed issues are still being investigated and the already implemented technologies
are being further improved.
Further.Development. Directions
The already mature technologies discussed in the previous section are continuously
being developed but new areas of research and new challenges appear on the scene.
These new issues come from various novel information technologies applied to
real business.
Nowadays, huge amounts of data are stored in various Web systems, typically in
the XML format. These data are crucial for business and, therefore, there is a need
x
to analyze them in a similar way as in traditional DWs. This requirement led to
several attempts to build data warehouses from Web data sources (e.g., Golfarelli,
Rizzi, & Vrdoljak, 2001) and to provide OLAP functionality for XML documents
(e.
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