Glossary of OLAP

Cube or Hypercube refers to a collection of multidimensional data. A hypercube called "GL" might contain data from the general ledger and be comprised of multiple dimensions usually found in a general ledger, such as accounts, costs centers, months, and versions. The accounts dimensions might contain base

Dimension - The "edges" of the cube are called dimensions. For example, in the "GL" hypercube, there might be four dimensions: accounts,costs centers, months, and versions.

Element - the individual items within each dimension are called elements. In the "GL" hypercube, the dimensions might contain base level elements such as Sales, Cost of Sales, Receivables, Payables, and calculated elements such as Net Income, Gross Margin % etc.

Hierarchy and Level - the elements at the base of the dimensional hierarchy are all at level 0. These elements contain the base-level input data. Level 1 elements are aggregations where all the children are level 0. Level 2 elements have at least one level 1 child. They may also have level 0 children.

Density- the number of cells in a table that are actually populated, expressed as a percentage of the theoretical volume of the table. Thus, a table which is 10% dense and has a theoretical table size of 5 million cells would contain 500,000 non-zero values.

Sparsity - the inverse of density. Thus, a table that is 10% dense would be 90% sparse.

Slice and Dice - refers to the ability for end users to view multidimensional data by navigating interactively -- rotating and pivoting how the dimensions are displayed as rows and columns, and drilling down to lower levels of detail.