OLAP Cubes: Basic operations
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This document discusses OLAP cubes and operations that can be performed on them. It describes cubes as a visual representation of data over dimensions like date or location. It explains how hierarchies allow controlling data granularity and how aggregating data brings higher-level data to measures. It also defines slicing, rotation, dice, and drilling operations that can be done on the cubes like fixing dimensions, changing axis, obtaining single data points, and navigating or changing granularity across dimensions.
OLAP Cubes: Basic operations
- 1. Sell volume Cube as a metaphor • In this example, a visual representation of multiple cubes over date dimension. OLAP Cubes Sthefan Berwanger
- 2. US TX NY CA Los Angeles San Diego New York BuffaloHouston Dallas August July 2 12 3 17 2012 Hierarchies • With hierarchies, it`s possible to control data granularity. Dimensions and hierarchies Sthefan Berwanger 2,5 3,0 1,5 2,5 4,0 2,5 3,0 4,0 0,5 1,0 2,5 1,5 1,0 3,0 0,0 2,5 0,5 1,0 2,5 1,5 3,0 0,5 1,0 3,0 Measures
- 3. 12,5 5,5 10,5 8,0 6,0 5,5 US TX NY CA August July 2012 Data aggregation • A query in a higher level of a dimension, brings aggregated data to a measure. Measures: Aggregated data Dimensions and hierarchies Sthefan Berwanger
- 4. Slicing • Two dimensions vary, and one is kept fixed. Stock 1/98 2/98 3/98 4/98 TEL PN +5% -2% +7% +4% PET PN +2,5% +3% +4% -1% BB PN -1% +1,3% +2,3% +2,1% LAME PN -2% +0,4% +1% +1,4% Fixed dimension: State Value: RJ Operations over OLAP Cube Sthefan Berwanger
- 5. Rotation • Change of dimensions axis. Fixed dimensions: State, Date, Stock Values: RJ, 2/98, BB PN Data TEL PN PET PN BB PN LAME PN 1/98 5% 2,50% -1% -2% 2/98 -2% 3% 1,30% 0,40% 3/98 7% 4% 2,30% 1% 4/98 4% -1% 2,10% 1,40% Operations over OLAP Cube Sthefan Berwanger
- 6. Dice • All dimensios are kept fixed to obtain a point of data, represented by the cross section of all axis. Ações 2/98 BB PN +1,3 % Fixed dimensions: State, Date, Stock Values: RJ, 2/98, BB PN Operations over OLAP Cube Sthefan Berwanger
- 7. Drilling • Drill up (Roll up): Decrease data granularity. • Drill down: Increase data granularity. • Drill Across: Navigation over dimension. US TX NY CADrill up Drill down Drill cross Operations over OLAP Cube Los Angeles San Diego New York BuffaloHouston Dallas Sthefan Berwanger