An OLAP cube (a.k.a. hypercube) is a multi-dimensional array of data designed for OLAP (online analytical processing) workloads. The term cube refers to a multi-dimensional dataset, which is also sometimes called a hypercube if the number of dimensions is greater than 3. In practice, an OLAP cube takes a spreadsheet-like structure and dimensionalizes it for the purposes of BI types of analysis such as company reports, budgets, or dashboards.
Historically OLAP cubes were highly regarded for having more intuitive user interfaces than the first generation data warehouses, and their ability to handle complex computations that were not possible with OLTP (a row-oriented database approach). When OLAP cubes were introduced in the 1990s, businesses could obtain insights into their company’s data trends, letting them see the “how” and “why” of their business for the first time.
However, cubes are relatively rigid, and they are not able to handle transactional data workloads. OLAP cubes must be built in advance and when a modification is necessary, the entire cube must be updated, which requires significant IT involvement and time.