This document provides an overview of dimensional modeling and loading dimensions and cubes using Oracle Warehouse Builder. It discusses key concepts like dimensional modeling, star schemas, slowly changing dimensions, and orphan management. It also describes how to define dimensional objects like dimensions and cubes in OWB and how the dimension and cube operators help to efficiently load data into those objects while handling issues like SCDs and orphans. Overall, it outlines how OWB supports dimensional modeling and ETL to help implement production data warehouse processes.

1. WELCOME Dimensional Modeling
with Oracle Warehouse
Builder 11.2.
Maren Escherman
BASEL BERN LAUSANNE ZÜRICH DÜSSELDORF FRANKFURT A.M. FREIBURG I.BR. HAMBURG MÜNCHEN STUTTGART WIEN
2011 © Trivadis
1
Title of Presentation Insert Header & Footer
Date

2. AGENDA
1. Introduction
 Dimensional modeling
 From the dimensional model to a relational star schema
2. Oracle Warehouse Builder: Dimensional Features
 How to build a data mart
3. ETL Accelerators
 Loading dimensions and cubes
 Slowly Changing Dimensions
 Invalid data (Orphan Management)
4. Performance Optimization
5. Summary
2011 © Trivadis
2
Title of Presentation  Insert  Header & Footer
Date

3. Oracle’s Data Warehouse Reference Architecture
2011 © Trivadis
3
Title of Presentation  Insert  Header & Footer
Date

4. Introduction – Dimensional Modeling
 Design technique proposed by Ralph Kimball
 became the predominant approach to designing
data marts
 predictable and cost effective
 Can be used for any physical form
 relational or multidimensional
 Understandability
 easier to understand and more intuitive to query
 Performance
 optimized for data querying
2011 © Trivadis
4
Title of Presentation  Insert  Header & Footer
Date

5. Dimensional Modeling 101
 Dimensional modeling always uses the concepts of facts (measures),
and dimensions (context).
 Dimensions are
 groups of hierarchies and
 the foundation of the fact table.
 Examples for Dimensions are
 Time (when)
 Customer (by whom)
 Geography (where)
 Product (what)
 Facts are additive figures such as quantity or cost per unit.
2011 © Trivadis
5
Title of Presentation  Insert  Header & Footer
Date

6. Semantic Loss
Relational Star Schema:
Zeit Tables, Columns
Produkt
Kalender_Hierarchy
Product_Hierarchy
Dimensional Model:
Dimensions, Levels,
Hierarchies, Facts, …
2011 © Trivadis
6
Title of Presentation  Insert  Header & Footer
Date

7. Avoid Semantic Loss
Relational Star Schema:
Zeit Tables, Columns
Produkt automatically created by OWB
Kalender_Hierarchy
Product_Hierarchy
Dimensional Model:
Dimensions, Levels,
Hierarchies, Cubes, …
OWB knows both worlds…
2011 © Trivadis
7
Title of Presentation  Insert  Header & Footer
Date

8. Dimensional Modeling Using OWB
 Define, deploy, and load dimensional objects
 explicitly separates dimensional design from physical implementation
 Support for ROLAP and MOLAP
 ETL accelerators: dimension and cube operator
 New 11g R2 features:
 Automated orphan management policies for
loading dimensional objects
 Oracle OLAP Cube-Organized Materialized
Views support
2011 © Trivadis
8
Title of Presentation  Insert  Header & Footer
Date

9. Dimensional Objects
 Easy to define by using dimension and cube wizard
 Additional OWB Meta-Objects are created
automatically (tables, sequences, bitmap
indexes, constraints, …)
 Implementation of best practices
2011 © Trivadis
9
Title of Presentation  Insert  Header & Footer
Date

10. Dimension Tables
 Table <DIM_NAME>_TAB
 Primary Key on DIMENSION_KEY
 For each level
 Group of columns
 Index on business key
 Manual vs. Automatic binding
 Automatic binding
- is easy, but …
- … overwrites ALL manual modifications
on the dimension table
 Manual Binding allows you to follow
your own naming conventions and design
patterns
2011 © Trivadis
10
Title of Presentation  Insert  Header & Footer
Date

11. «Solved» Dimensions
 “Solved “ dimensions contain records for higher level elements (control
rows)
 enable you to link fact data to a dimension at any level
 Control Rows have
 Negative surrogate Keys
 NULL attributes for lower levels
2011 © Trivadis
11
Title of Presentation  Insert  Header & Footer
Date

12. Time Dimension
 Time dimension is not «solved»
 use 01.01.2011 for referencing «January 2011»
 Primary Key is a DATE attribute
 was a NUMBER in pre-11.2 releases
 allows partitioning of fact table by date
 Mapping to load the time dimension table is generated by OWB
 Different hierarchies are supported
 week hierarchy
 fiscal year hierarchy
2011 © Trivadis
12
Title of Presentation  Insert  Header & Footer
Date

13. Fact Table
 Table <CUBE_NAME>_TAB
 One column per
 measure
 referenced dimension
 Bitmap Index and foreign key for each dimension attribute
 Unique key for the combination of dimension attributes (optional)
 No partitioning! No compression!
2011 © Trivadis
13
Title of Presentation  Insert  Header & Footer
Date

14. Deployment
Design Repository Target Schema
Deploy Aggregation Materialized
Cube
Views
Dimension
Dimension
Deploy Data Objects
View
2011 © Trivadis
14
Title of Presentation  Insert  Header & Footer
Date

15. Dimension/Cube Operator
 Used for loading data into a dimension/cube
 can do a lot of tedious work for you
 Are actually pluggable mappings
 Dimension Operator
 populates dimension surrogate key
 realizes SCD (Slowly Changing Dimensions) updates
 handles invalid dimension records
 Cube Operator
 looks up surrogate keys based on business key
 handles slowly changing dimensions
 handles invalid cube records
2011 © Trivadis
15
Title of Presentation  Insert  Header & Footer
Date

16. Dimension Operator
 Supports two loading types:
 Load
 Remove
 Allows deduplication of level
elements
 Creates OWB$TEMP Tables
when mapping is deployed
 needed to provide some of the
hierarchy management and
loading functionality
2011 © Trivadis
16
Title of Presentation  Insert  Header & Footer
Date

17. Slowly Changing Dimension
 Support for SCD Types 1, 2 and 3
 Type 1: Do not store history
 Type 2: Store the complete
change history
 Type 3: Store only the previous
value
 User can specify which attributes
trigger a new version
 only use from 10.2.0.3 upwards
 bugs in earlier versions
2011 © Trivadis
17
Title of Presentation  Insert  Header & Footer
Date

18. SCD: «Under The Hood»
 Income_Level and Marital_Status trigger a new version
 For all other records only the most current record is updated
INCOME FIRST LAST MARITAL JOB VONDAT BISDAT
B Constantin Welles single Teacher 05-SEP-07 12-OCT-09
C Constantin Welles single Teacher 12-OCT-09 17-AUG-10
C Constantin Welles married Policeman 17-AUG-10 31-DEC-99
5-Sept-07 – Constantin Welles becomes customer.
12-Okt-09 – Constantin Welles gets a raise.
17-Aug-10– Constantin Welles marries.
??? – Constantin Welles has a new job.
2011 © Trivadis
18
Title of Presentation  Insert  Header & Footer
Date

19. SCD: «Under The Hood»
 Kimball Design Tip #15: Combining SCD Techniques
 “For all prior dimension rows for a given customer, the current roll-up attribute
will be overwritten to reflect the current state of the world.”
 Kimball’s «Hybrid SCD» is not implemented by dimension operator
2011 © Trivadis
19
Title of Presentation  Insert  Header & Footer
Date

20. Orphan Management
 What is an «orphan»?
 Dimension level element with no or invalid parent level attribute
 Fact with no or invalid dimension reference
 Available for dimensions and cubes
 Error tables store any records that are detected as anomalous.
Specify values used by
the default record
2011 © Trivadis
20
Title of Presentation  Insert  Header & Footer
Date

21. Dimension Operator: «Behind the Scenes» - 1
2011 © Trivadis
21
Title of Presentation  Insert  Header & Footer
Date

22. Dimension Operator: «Behind the Scenes» - 2
2011 © Trivadis
22
Title of Presentation  Insert  Header & Footer
Date

23. Dimension Operator: «Behind the Scenes» - 3
2011 © Trivadis
23
Title of Presentation  Insert  Header & Footer
Date

24. Cube Operator
 Loading Type
 INSERT LOAD
 LOAD
- source data is merged into
the cube
 REMOVE
 Enable Source Aggregation
 Handles slowly changing
dimensions
 Orphan Managment
2011 © Trivadis
24
Title of Presentation  Insert  Header & Footer
Date

25. Cube Operator: «Behind the Scenes»
Source Aggregation
Dimension Surrogate
Key Lookup Orphan Management
2011 © Trivadis
25
Title of Presentation  Insert  Header & Footer
Date

26. Features, Features, Features, …
 Loading dimensions
 Physical and logical deletes
 Dimensions without surrogate key
 History Logging Policy
 Support Multiple History Loading
 Out of Order History Loading
 Standard DML Error Logging
 Hierarchy Versioning
- Attribute changes are also recorded for higher levels
 Loading cubes
 Degenerate dimensions
 Different source aggregation functions (SUM, AVG, …)
 Different update functions (+=, -=, …)
2011 © Trivadis
26
Title of Presentation  Insert  Header & Footer
Date

27. It’s all about performance!
 OWB can create
 Relational MViews
 Cube Based Mviews
 Mviews are created when deploying aggregation of cube
 MViews are no meta objects in OWB
 Relational Mviews are recreated every time you deploy
 MView Features like «fast refreshing» and «partition change tracking» are not
supported
 Hint: Select precompute for the leaf level also to avoid OLAP Bug.
2011 © Trivadis
27
Title of Presentation  Insert  Header & Footer
Date

28. Licenses
 You need
 Data Integrator Enterprise Edition (formerly Warehouse Builder Enterprise ETL)
for
- SCD 2 and 3 support
- Orphan management
 OLAP Option for
- Creation of Materialized Views
2011 © Trivadis
28
Title of Presentation  Insert  Header & Footer
Date

29. Be aware of …
 You can define default values without orphan management.
 Degenerate dimensions are possible (with 11.2)
 Each cube must have at least one measure
 For factless fact tables use one «dummy» fact with the default value 1
 Either all dimensions levels have a surrogate key or none
 Dimensional operators can also be used as source operators.
2011 © Trivadis
29
Title of Presentation  Insert  Header & Footer
Date

30. Everything has to fit together
Dimension
Dimension Configuration
Settings
Cube
Configuration Operator
Properties
Cube
Settings
2011 © Trivadis
30
Title of Presentation  Insert  Header & Footer
Date

31. Open the toolbox!
 Take everything that suits your
project-specific requirements
 You should have good reasons not to
use dimensional operators
 Model dimensions and cubes to avoid
semantic loss
 Do prototyping!
 Learn how things work
 Good understanding of the underlying
technologies (e.g. OLAP) is necessary
 With or without dimensional operators:
Use the same design pattern everywhere!!
2011 © Trivadis
31
Title of Presentation  Insert  Header & Footer
Date

32. Summary
 Oracle Warehouse Builder offers a broad range of support for
dimensional objects.
 When using these features you …
 … can efficiently implement your ETL processes
 … are «production-ready» in a shorter time span
 … avoid semantic loss
 … achieve high quality in your implementation
 … have a standardized design pattern in your dimension and cube loading
mappings
2011 © Trivadis
32
Title of Presentation  Insert  Header & Footer
Date

33. THANK YOU.
Trivadis AG
Maren Eschermann
Europa-Strasse 5
8152 Glattbrugg
Tel. +41-44-808 70 20
Fax +41-44-808 70 21
info@trivadis.com
www.trivadis.com
BASEL BERN LAUSANNE ZÜRICH DÜSSELDORF FRANKFURT A.M. FREIBURG I.BR. HAMBURG MÜNCHEN STUTTGART WIEN
2011 © Trivadis
33
Title of Presentation Insert Header & Footer
Date