Multidimensional database

Multidimensional databases are variously (depending on the context) data aggregators which combine data from a multitude of data sources; databases which offer networks, hierarchies, arrays and other data formats difficult to model in SQL; or databases which give a high degree of flexibility in the definition of dimensions, units, and unit relationships, regardless of data format.

Multi-dimensional databases are especially useful in sales and marketing applications that involve time series. Large volumes of sales and inventory data can be stored to ultimately be used for logistics and executive planning. For example, data can be more readily segregated by sales region, product, or time period.

While many of the major database vendors have recognized and implemented at least a partial solution, most frequently they rely upon a Star schema database design. However, the star design for relational databases can result in "sparse data," or sets of ordered data with large gaps between data entries. While modern database engines use strategies to limit the impact of sparse data sets on query performance, such as compressing large blocks of empty data elements for quicker access, star databases can still present worse performance than other alternatives.