jikalau database relational menyimpan semua data dalam bentuk baris dan kolom, maka multidimensional dataset terdiri dari sumbu dan sel.
The rows axis consists of the members 'All products', 'Books', 'Fiction', and so forth, and the columns axis consists of the cartesian product of the years '2000' and '2001', and the calculation 'Growth', and the measures 'Unit sales' and 'Dollar sales'. Each cell represents the sales of a product category in a particular year; for example, the dollar sales of Magazines in 2001 were $2,426.
This is a richer view of the data than would be presented by a relational database. The members of a multidimensional dataset are not always values from a relational column. 'Total', 'Books' and 'Fiction' are members at successive levels in a hierarchy, each of which is rolled up to the next. And even though it is alongside the years '2000' and '2001', 'Growth' is a calculated member, which introduces a formula for computing cells from other cells.
The dimensions used here — products, time, and measures — are just three of many dimensions by which the dataset can be categorized and filtered. The collection of dimensions, hierarchies and measures is called a cube.
Although some multidimensional databases store the data in multidimensional format, I shall argue that it is simpler to store the data in relational format.
sumber : http://mondrian.pentaho.com/documentation/olap.php