Oracle Express is a multi-dimensional database and application development environment for building OLAP applications.
Normal relational databases store data in two-dimensional tables and analytical queries against them are normally very slow. Express provides its own specialized database for storing muti-dimensional data. Data in a multi-dimensional database is stored as business people view it, allowing them to slice and dice the data to answer business questions. When designed correctly, an OLAP database will provide must faster response times for analytical queries.