multidimensional databases
Multidimensional databases, such as OLAP, present
data hierarchically by using cubes, dimensions and elements. A cube is a
collection of dimensions which contain a number of elements. You may have, for
example, a Sales cube containing a Product dimension containing individual
product elements; a Time dimension containing years as its elements, and a
Region dimension containing countries. These hierarchical structures are
difficult to represent efficiently in SQL. Multidimensional databases are
particularly useful where the data has a Time dimension and so are often used
in planning applications.