MOLAP

Multidimensional OLAP (MOLAP), is a multidimensional optimization of OLAP. It is often applied to data warehouse information, which is stored in fact tables. In a star schema, these tables contain the basic information and dimensional links to supporting attribute tables.

MOLAP models this data in a multi-dimensional array, rather than tables of records and fields (i.e. a relational model). Because arrays can be indexed against fixed references, queries are very fast, and storage space much smaller (between a tenth and a half), but at the expense of scalability.

Examples of products that use MOLAP arrays are Essbase and Applix.

Until recently most MOLAP solutions have been expensive proprietary solutions frequently based on a per seat or processor licensing model. Users wishing for a free olap solution had little choice, apart from mondrian which was ROLAP. There is now an open soure MOLAP server - [http://www.palo.net Palo] which includes an excel add-in for reporting purposes