OLAP Cubes & Rollups

Concepts: dmOlapCubes

Pre-Computing Every Dimension Combination An OLAP cube is a summary table that pre-computes aggregates for every combination of dimensions. Revenue by product. Revenue by region. Revenue by product AND region. Revenue by product AND region AND month. If you have 3 dimensions with 10 values each, the cube has 10 x 10 x 10 = 1,000 cells. Each cell stores a pre-computed SUM. Modern cloud warehouses do not use literal cubes (multidimensional arrays). They use flat summary tables with GROUP BY ROLLUP or GROUP BY CUBE to generate all combinations. But the concept is the same: pre-compute aggregates at every granularity so any dashboard filter combination is answered instantly. ROLLUP vs CUBE vs GROUPING SETS CUBE generates 2^n grouping combinations where n is the number of dimensions. With 5 dim