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Fundamentals of Data Cube & OLAP Operations. Data as Table. Multidimensional (3D) Table. Sample Data cube. Cuboids. Summarization - Cuboids. data at different degrees of summarization
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Summarization - Cuboids • data at different degrees of summarization • we can construct a lattice of cuboids, each showing the data at a different level of summarization, or group by (i.e., summarized by a different subset of the dimensions). • The lattice of cuboids is then referred to as a data cube. • lattice of cuboids forming a data cube for the dimensions time, item, location, and supplier.
Base & Apex • The cuboid which holds the lowest level of Summarization is called the base cuboid. • 3-D (non-base) cuboid for time, item, and location, summarized for all suppliers. • The 0-D cuboid which holds the highest level of summarization is called the apex cuboid. • The apex cuboid is typically denoted by all.
OLAP Operations • Slice • Dice • Drill • Drill / Roll-up • Drill-down • Drill-across • Drill - through • Pivot / Rotate
Slice Slice ? • C[time, items, cities] City = chennai
Dice Dice ? • C[time, items, cities] time = Q1, Q2 & items = TV, DVD
Drill - up Drill-up ? • C[time, items, cities] T1 = Q1&Q2 T2 = Q3&Q4
Drill-down Drill-down ? • C[time, items, cities] Quarter = Month
Drill - across Drill - across ? • C[time, items, cities] City -> Month
Drill - through Drill - through ? • C[time, items, cities] RDBMS
Pivot Pivot ? • C[time, items, cities] Cities <-> time