Description
Data warehousing concepts suggests to use bridge-tables to implement many-to-many relationships between cube & dimension or between two dimensions.
Here are few links explaining the bridge-tables
http://www.pythian.com/blog/implementing-many-to-many-relationships-in-data-warehousing/
http://www.kimballgroup.com/2012/02/design-tip-142-building-bridges/
http://stackoverflow.com/questions/2785158/star-schema-fact-1n-dimension-how
http://www.askjohnobiee.com/2013/08/how-to-bridge-tables-and-many-to-many.html
If we look at the following schema :
User :
| ID | Name | Gender |
| 1 | A | M |
| 2 | B | M |
| 3 | C | F |
User interests :
| UserID | Sports ID |
| 1 | 1 |
| 1 | 2 |
| 2 | 1 |
| 2 | 2 |
| 2 | 3 |
Sports :
| SportsID | Description |
| 1 | Football |
| 2 | Cricket |
| 3 | Basketball |
User Interests is the bridge table which is capturing the many-to-many relationship between Users and Sports.
If we have a fact as follows :
| UserId | Revenue |
| 1 | 100 |
| 2 | 50 |
If analyst is interested in analyzing with respect to user's interest, then the report would the following :
| User Interest | Revenue |
| Football | 150 |
| Cricket | 150 |
| BasketBall | 50 |
Though the individual rows are correct and the overall revenue is actually 150, looking at above report makes people assume that overall revenue is 350.
The feature ask here is to optionally flatten the selected fields, if fields involved are coming from bridge tables in join path. If flattening is enabled, the report would be the following :
| User Interest | Revenue |
| Football, Cricket | 100 |
| Football, Cricket, BasketBall | 50 |
Attachments
Attachments
Issue Links
- is related to
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LENS-788 Option to do flattening of columns on bridge tables later
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- Closed
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