1. Your friends / colleagues can watch this session Live on !
Go to my Twitter
I pinned the Youtube url of the session

2. Speaker Tristan Malherbe Power BI Consultant at AZEO
Power BI User Group Leader: Club Power BI, France
Power BI Data Stories Publisher
Follow me on Linkedin and Twitter

3. Power BI User Group (PUG) Copenhagen
Welcome !
Power BI User Group (PUG)
Copenhagen

4. Tristan Malherbe Power BI Consultant and User Group Leader
Many to Many in DAX
Tristan Malherbe
Power BI Consultant and User Group Leader

5. The Issue

6. Agenda Tabular modelling best practices Use Case
Comparaison & Conclusion

7. Tabular Modelling (1/2) Star Schema Denormalized Dimensions
In-memory columnar storage: Vertipaq engine
Double advantage:
- Optimized Storage
- Easier analysis

8. Tabular Modelling (2/2) Relationship conditions Relationship direction
Common Key
Uniqueness from (at least) one side of the relationship
Relationship direction
One  Many : From Dimensions to Facts

9. Use Case Presentation

10. M2M: Between Two Fact Tables
 Solution: Finding (at least) a common Dimension with identical grain 1 1 * 1 1 * * *

11. M2M: Between a Fact Table and a Dimension Table
1st Step: Creating a Bridge table 1 1 * * *
2nd step: Using DAX language – 4 methods

12. Bi-directional Filtering
1. At Data Model level
Available on Power BI Desktop and SSAS 2016.
Simple but « expensive » and generates ambiguous models
Acceptable in a single fact table model
2. At Measure level
Dax Pattern: = Calculate ( [Measure] , CrossFilter ( ManySide , OneSide , Both ) )
Available on Excel 2016, Power BI Desktop and SSAS 2016.
Local impact but need to replicate your efforts.

13. Context Transition Method
3. A Method purely based on contexts
Row Context  Filter Context thanks to the power of the Calculate () DAX function
Dax Pattern: = Calculate ( [Measure] , Filter ( LeftDim , Calculate( Countrows(Bridge) ) > 0 ) )
Explanation:
Filter Expression
Calculate( Countrows(Bridge) ) > 0
Available on Excel 2010, 2013, 2016, SSAS et Power BI Desktop

14. Bridge Method 4. A Method based on the concept of « expanded tables »
Dax Pattern: = Calculate ( [Measure] , Bridge )
The Bridge table inherits the columns coming from its dimensions
Available on Excel 2010, 2013, 2016, SSAS and Power BI Desktop

15. The best method ?
 Bridge
Bonus: Pro-rating each trainer’s turnover