1. OLAP Seminar1 Sanjay Goil Alok Choudhary Department of Electrical & Computer Engineering and Center for Parallel and Distributed Computing, Northwestern University, Technological Institute 데이터베이스 연구실 석사 2 학기 임성은 Sparse Data Storage of Multi-Dimensional Data for OLAP and Data Mining

2. OLAP Seminar2 zIntroduction zMulti-dimensional databases yMulti-dimensional Arrays yCompressed Multi-dimensional Arrays zSparse Data Storage yBit-Encoded Sparse Storage(BESS) zOther Sparse Storage Schemes yBit-Index-Value pairs yOffset-Value pairs yCompressed Sparse Dimensions ySparse-Dense split storage Contents

3. OLAP Seminar3 zData Access Operations in OLAP and Data Mining yData Cubes yBasic Operations zData Access Performance yOperations yChoosing a sparse structure zPerformance Results yDecoding dimension index values yRetrieval along a dimension and Range Queries yAggregation along a combination of dimensions zConclusions Contents

4. OLAP Seminar4 zIntroduction of BESS yretrieval of dimensional index for OLAP operation along specified dimensions : bit operation zA comparison with other sparse data structure zAnalysis and performance results in terms of design parameters : ynumber of dimensions, dimension sizes, sparsity of data, cell size Introduction

5. OLAP Seminar5 zMulti-Dimensional databases Multi-dimensional databases

6. OLAP Seminar6 zMulti-Dimensional databases Multi-dimensional databases

7. OLAP Seminar7 zMulti-Dimensional Arrays Multi-dimensional databases

8. OLAP Seminar8 zCompressed Multi-Dimensional Arrays yFigure 3: Storage of data in chunks Multi-dimensional databases

9. OLAP Seminar9 zSparse Data Storage yFigure 4: Dense and sparse chunk storage for the datacube Sparse Data Storage

10. OLAP Seminar10 zBit-Encoded Sparse Storage (BESS) yFigure 5: Bit Encoded Sparse Storage Sparse Data Storage

11. OLAP Seminar11 zBit-Encoded Sparse Storage (BESS) Sparse Data Storage

12. OLAP Seminar12 zBit-Encoded Sparse Storage (BESS) Sparse Data Storage

13. OLAP Seminar13 zIndex-Value pairs zOffset-Value pairs zCompressed Sparse Dimensions Other Sparse Storage Schemes Figure 8 : Sparse data structures for a sample sparse array (a) Index-Value pairs (b) Offset- Value pairs (c) Compressed Sparse Dimensions Figure 8 : Sparse data structures for a sample sparse array (a) Index-Value pairs (b) Offset- Value pairs (c) Compressed Sparse Dimensions

14. OLAP Seminar14 zSparse-Dense split storage Other Sparse Storage Schemes

15. OLAP Seminar15 zData Cubes yPivoting(Rotating) : rotating the cube to change the dimensional orientation of a report or page on display ySlicing-dicing : selecting some subset of the cube yRoll-up : going up the hierarchy to higher levels of generation yDrill-Down : traversing the hierarchy from lower to higher levels of detail yTrend analysis over sequential time periods Data Access Operations in OLAP

16. OLAP Seminar16 zBasic Operations yRetrieval of a random cell element yRetrieval along a dimension or a combination of dimensions Data Access Operations in OLAP

17. OLAP Seminar17 zBasic Operations yRetrieval for values of dimensions within a range (Range Queries) yAggregation operations on dimensions Data Access Operations in OLAP

18. OLAP Seminar18 zBasic Operations yAggregation operations on dimensions Data Access Operations in OLAP

19. OLAP Seminar19 zBasic Operations yMulti-dimensional Aggregation (Generalization/Consolidation: lower to higher level in hierarchy) Data Access Operations in OLAP

20. OLAP Seminar20 zData Access Performance Data Access Performance

21. OLAP Seminar21 zOperations yRetrieval of a random cell element yRetrieval along a dimension yAggregation of a dimension zChoosing a sparse structure Data Access Performance

22. OLAP Seminar22 zDecoding dimension index values Performance Results

23. OLAP Seminar23 zDecoding dimension index values Performance Results

24. OLAP Seminar24 zDecoding dimension index values Performance Results

25. OLAP Seminar25 zDecoding dimension index values Performance Results

26. OLAP Seminar26 zRetrieval along a dimension and Range Queries Performance Results

27. OLAP Seminar27 zAggregation along a combination of dimensions Performance Results

28. OLAP Seminar28 zPerformance results show better performance for OLAP queries using BESS over other storage schemes. Conclusions