Nov 8 2002 DOLAP 2002McLean USA
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
Nov 8 2002 DOLAP 2002McLean USA
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
Nov 8 2002 DOLAP 2002McLean USA
Multidimensional Models
Date
Gender
City Country
Static organization of data
Fact Table
Nb of Births
Star or Snowflake representation
Issues
Nov 8 2002 DOLAP 2002McLean USA
First Case StudyLocation dimension:
2001 2002
D1 100 100
D2 50 100
D3 100 50
Query: « Total number of births per year and city ? »
2001 2002 Evo
C1 150 100
C2 100 150
2001 2002 Evo
C1 150 200
C2 100 50
2001 2002 Evo
C1 100 100
C2 150 150
C1 C2
D1 D2 D3
2001
C1 C2
D1 D2 D3
2002
1. Exact view 2. Mapped info into 2001 organization
3. Mapped info into 2002 organization
Issues
Nov 8 2002 DOLAP 2002McLean USA
Second Case StudyLocation dimension:
2001 2002
D 100 -
D1 - 150
D2 - 50
Query: « Total number of births per year and district ? »
2001 2002 Evo
D 100 - ?
D1 - 150 ?
D2 - 50 ?
2001 2002 Evo
D 100 200
2001 2002 Evo
D1 40* 150
D2 60** 50
C1
D
2001
1. Exact view 2. First Structure 3. Second Structure
2002
C1
D1 D2
* D1 ~ 40 % of the births of D1** D2 ~ 60 % of the births of D1
Issues
Nov 8 2002 DOLAP 2002McLean USA
Existing Solutions (1/2)
Related works
• 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
Nov 8 2002 DOLAP 2002McLean USA
Existing Solutions (2/2)
Related works
• Tracking history models(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)
Nov 8 2002 DOLAP 2002McLean USA
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
Proposal
Nov 8 2002 DOLAP 2002McLean USA
Evolutions in multidimensional structures
Proposal
Dimension schema evolution
•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
Evolution members: simple operations
•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
Evolution on members : Exples of complex operations•Decreasing: splitting and deletion•Increasing: creation and merging•Partial annexation: splitting and merging
Nov 8 2002 DOLAP 2002McLean USA
Conceptual Model: Temporal Multidimensional Schema
Zaïre Dem. Rep. of Congo
[1990 ; 1997] [1997 ; Now]
Temporal Dimension: - Evolution of the hierarchical
structure of the members
Mapping Relationship: - keeping transition links between
member versions D1
D
D2
f : x x
f : x 0.4 x
f : x 0.6 x
f : x x Confidence factor:
- Evaluation of the confidence associated to a mapping
(exact mapping)
(approximated mapping) (exact
mapping)
(approximated mapping)
- Evolution of the members of a dimension
Member Version:
V1
D1 D2 D3
[98 ; 02] [98 ; 02]
[98 ; 00] [01 ; 02]
V2
P1
Proposal
Nov 8 2002 DOLAP 2002McLean USA
Conceptual Model: MultiVersion Fact Table
Temporal Modes of Presentation: - Modes for the presentation of a
multidimensional request
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
- a valid, unchanged structure over its given valid time.
Structure Version:
96 99 01
VS.1 VS.2 VS.3
- Temporally consistent mode - version VS.1- version VS.2- version VS.3
Proposal
Nov 8 2002 DOLAP 2002McLean USA
Logical Model
- Temporal Modes of Presentation integrated in a new dimension.
Date
Gender
City Country
Fact Table
Nb of births
Confidence factor
- Confidence factors integrated as a new measure
T.M.P.
Implementation
Nov 8 2002 DOLAP 2002McLean USA
Architecture
MultiVersion Data Warehouse
OLAP MultiVersion CubeTemporal Data Warehouse
- Extract the Structure Versions- Compute the transitive… of the
Mapping relation - Mapping of data
- Data Agregation- Multidimensional
Indexation
Implementation
Nov 8 2002 DOLAP 2002McLean USA
PrototypeSale numbers and production cost per
product, district and month
Table de Faits
FK1 LocIDFK2 The_dateFK3 ProdID
VenteCout
Produits
PK ProdID
TypeProduitProduitFromTo
Time
PK The_date
The_monthThe_yearMonth_of_yearQuarter
Localisation
PK MemberID
MemberNameParentIDLevelNameFromTo
Conversions
MemberFromMemberToFacteurVenteFacteurCoutFiabiliteVenteFiabiliteCoutFromTo
Metadonnees
Star Schema of the temporal Data Warehouse
Implementation
Nov 8 2002 DOLAP 2002McLean USA
Development ToolsVisual Basic Interface and
Proclarity Components
OLAP MultiVersion Cube(SQL Server Analysis
Service)
Access to the data cube
Data warehouse Repository (SQL Server)
Access to meta data
Implementation
Nov 8 2002 DOLAP 2002McLean USA
End User Tools for Analysis
Implementation
Example of Metadata: describes the evolutions of the element pointed in the grid.
Grid: presents the values and their confidence factors
Comparative study:Two temporal modes are represented
Dimensions control: used to navigate trough the cube
Nov 8 2002 DOLAP 2002McLean USA
End User Tools for Navigation:find the « best version »
Implementation
Parameters for each type of confidence
Rank of the temporal modes of presentation
Nov 8 2002 DOLAP 2002McLean USA
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