Question - What’s an OLAP Cube?
Answer -
The idea behind OLAP was to pre-compute all calculations that are needed for reporting. Generally, calculations are done through a scheduled batch job processing at non-business hours when the database server is normally idle. The calculated fields are stored during a special database, called an OLAP Cube.
An OLAP Cube doesn’t need to loop through any transactions because all the calculations are pre-calculated, providing instant access.
An OLAP Cube may be a snapshot of knowledge at a selected point in time, perhaps at the top of a selected day, week, month, or year.
At any time, you’ll refresh the Cube, using the present values within the source tables.
With very large data sets, it could take an appreciable amount of your time for Excel to reconstruct the Cube.
But with the info sets we’ve been using (just a few thousand rows), the method appears to be instantaneous.