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A Multidimensional and Multiversion Structure for OLAP Applications

A Multidimensional and Multiversion Structure for OLAP Applications. Mathurin Body 1,2 , Maryvonne Miquel 2 , Yvan Bédard 1,2 , Anne Tchounikine 2 1 Centre de recherche en Géomatique, Univ Laval, Québec, Canada 2 Institut National des Sciences Appliquées, Lyon, France. Purpose.

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A Multidimensional and Multiversion Structure for OLAP Applications

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  1. A Multidimensional and Multiversion Structure for OLAP Applications Mathurin Body1,2, Maryvonne Miquel2, Yvan Bédard1,2, Anne Tchounikine2 1 Centre de recherche en Géomatique, Univ Laval, Québec, Canada 2 Institut National des Sciences Appliquées, Lyon, France DOLAP 2002 McLean USA

  2. Purpose • Handle evolutions in Multidimensional Structures • Compare data into static structures • Provide a new conceptual model • Define evolution operators • Give solutions and tools for implementation DOLAP 2002 McLean USA

  3. Issues Date Nb of Births Fact Table City Country Gender Static organization of data Multidimensional Models • Star or Snowflake representation DOLAP 2002 McLean USA

  4. Issues C1 C2 C1 C2 D1 D2 D3 D1 D2 D3 2001 2002 First Case Study Location dimension: Query: « Total number of births per year and city ? » 1. Exact view 2. Mapped info into 2001 organization 3. Mapped info into 2002 organization DOLAP 2002 McLean USA

  5. Issues C1 C1 D1 D2 D 2002 2001 Second Case Study Location dimension: Query: « Total number of births per year and district ? » 1. Exact view 2. First Structure 3. Second Structure * D1 ~ 40 % of the births of D1 ** D2 ~ 60 % of the births of D1 DOLAP 2002 McLean USA

  6. Related works Existing Solutions (1/2) • Updating models • (M. Blaschka, C. Hurtado, A.O. Mendelzon and A. Vaisman) • Pragmatic way • Allow temporal comparison • Corrupt data • lose data (e.g. deletion of a member) • Hiding evolutions DOLAP 2002 McLean USA

  7. Related works Existing Solutions (2/2) • Tracking historymodels • (R. Bliujute, P. Chamoni and S. Stock, J. Eder and C. Koncilia, R. Kimball, A.O. Mendelzon and A. Vaisman, T.B. Pedersen, C.S. Jensen and C.E. Dyreson ) • Temporally consistent representation • Evolutions kept • Only one representation of data (no comparison across time) • Limit of data analysis • Mapping functions (J. Eder and C. Koncilia) • Timestamps on the elements of multidimensional database (A.O. Mendelzon and A. Vaisman) DOLAP 2002 McLean USA

  8. Proposal Our Objectives • For the administrators: • Integrate all kinds of evolution in a multidimensional structure • Take into account complex dimension structures • For the users: • Choose between different modes of representation • End user tools for analyse DOLAP 2002 McLean USA

  9. Proposal Dimension schema evolution Evolution members: simple operations Evolution on members : Exples of complex operations • Creation and deletion of a dimension • Creation and deletion of a hierarchy • Creation and deletion of a level • Move of a level in the hierarchical schema structure • Creation of a member • Deletion of a member • Transformation of a member (change of an attribute, its name or meaning…) • Merging of n members into one member • Splitting of one member into n members • Reclassification of a member in the dimension structure • Decreasing: splitting and deletion • Increasing: creation and merging • Partial annexation: splitting and merging Evolutions in multidimensional structures DOLAP 2002 McLean USA

  10. Proposal • Member Version: Zaïre Dem. Rep. of Congo - Evolution of the members of a dimension [1990 ; 1997] [1997 ; Now] • Temporal Dimension: P1 - Evolution of the hierarchical structure of the members V1 V2 [98 ; 02] [98 ; 02] [98 ; 00] [01 ; 02] D1 D2 D3 • Mapping Relationship: - keeping transition links between member versions D1 f : x  0.4x (approximated mapping) (exact mapping) f : x  x D f : x  x (exact mapping) • Confidence factor: f : x  0.6x D2 (approximated mapping) - Evaluation of the confidence associated to a mapping Conceptual Model: Temporal Multidimensional Schema DOLAP 2002 McLean USA

  11. Proposal • Structure Version: - a valid, unchanged structure over its given valid time. • Temporally consistent mode • version VS.1 • version VS.2 • version VS.3 • MultiVersion Fact Table: - Fact Table with different temporal modes of Presentation - Automatically deduced from the temporally consistent fact table, the temporal dimensions and the mapping relationship Conceptual Model: MultiVersion Fact Table VS.1 VS.2 VS.3 96 99 01 • Temporal Modes of Presentation: - Modes for the presentation of a multidimensional request DOLAP 2002 McLean USA

  12. Implementation Date Fact Table Nb of births City Country Gender T.M.P. Logical Model - Temporal Modes of Presentation integrated in a new dimension. - Confidence factors integrated as a new measure Confidence factor DOLAP 2002 McLean USA

  13. Implementation Temporal Data Warehouse MultiVersion Data Warehouse OLAP MultiVersion Cube Architecture • Extract the Structure Versions • Compute the transitive… of the Mapping relation • Mapping of data • Data Agregation • Multidimensional Indexation DOLAP 2002 McLean USA

  14. Implementation Star Schema of the temporal Data Warehouse Prototype Sale numbers and production cost per product, district and month DOLAP 2002 McLean USA

  15. Implementation Development Tools Visual Basic Interface and Proclarity Components Access to the data cube Access to meta data OLAP MultiVersion Cube (SQL Server Analysis Service) Data warehouse Repository (SQL Server) DOLAP 2002 McLean USA

  16. Implementation End User Tools for Analysis Dimensions control: used to navigate trough the cube Comparative study: Two temporal modes are represented Grid: presents the values and their confidence factors Example of Metadata: describes the evolutions of the element pointed in the grid. DOLAP 2002 McLean USA

  17. Implementation End User Tools for Navigation:find the « best version » Parameters for each type of confidence Rank of the temporal modes of presentation DOLAP 2002 McLean USA

  18. Conclusion • A temporal multidimensional model for supporting evolutions on multidimensional structures • USER • Navigate through different modes of presentation • Choose the interpretation he wants to give to his request • Be guide to select its best representation • Have access to metadata describing all evolutions of member versions • DESIGNER AND ADMINISTRATOR • Model different kinds of hierarchical dimensions • Take into account all types of evolutions in the multidimensional structures • Implement this model on commercial OLAP environment • Extension • choose a temporal mode of presentation for each dimension DOLAP 2002 McLean USA

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