A data cube is a multi-dimensional database that stores, analyzes and reports large amounts of data. Cubes are used to identify business trends that signal opportunities or problems. The multidimensional aspect of cubes refers to the storage of multiple data elements. A cube can be used to track and compare the number of sales and type of product sold by each salesman. The cube can then be used to track how salesmen are performing, what they are selling, and when.
MS Excel pivot table is an example of a data cube that can be used in Excel. Data cubes can be accessed through the Internet using applications such as MS Active X controls or active server pages. By using MS query a user can save results from a query and later open the files through Excel and publish the results to the Web.
Storing Data Cubes
There are three basic ways to store data cubes: MOLAP, ROLAP, and HOLAP. MOLAP, or “Multidimensional Online Analytical Programming,” stores the aggregates and base level data in individual files. This requires more disk space but is a faster method of retrieving the data.
ROLAP “Relational Online Analytical Processing,” stores the aggregates in tables next to the base level data. This requires less disk space than MOLAP storage but sacrifices a little bit of speed. Hybrid Online Analytical Processing, HOLAP, is a cross between MOLAP and ROLAP. Hybrid OLAP saves the aggregates into a MOLAP file while storing the base level data in a database.
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