Examples include Oracle??™s Express Server and
Oracle??™s Hyperion Essbase, as well as the Microsoft Analysis Services. Such MOLAP
engines handle queries extremely quickly and work best when the data is not
updated frequently (because the cube-generation process takes time). Oracle??™s
Essbase offering provides a MOLAP engine that can be used in conjunction with a
variety of relational database engines.
OLAP functionality became more common in relational databases since star schema
containing summary levels are supported to various degrees in many databases and
because there is an increased need for very frequently updated data. When used in
this fashion, the interaction is called ROLAP, which stands for Relational Online
Analytical Processing. Tools that can work against either relational databases or
MOLAP engines are sometimes referred to as hybrid tools. For ROLAP deployment,
Oracle??™s Business Intelligence tools and several other tools can leverage ANSI standard
analytic functions built into the database as SQL extensions and can also access
the OLAP Option, a MOLAP cube within the relational database, via SQL.
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