Get group key from bridge table
- by Mads Jensen
I'm developing an ETL process, and need a bridge table for a one-to-many relationship between a fact table and a dimension table (MySQL database). There is a limited number of combinations (some thousands), so I want to re-use group keys from the bridge table to to limit the size.
Any group of dimensions belonging to a fact row will consist of a number of dimension keys (1 to around 15), assigned to a unique group key, as below:
group_key | dimension_key
-----------------------
1 | 1
1 | 3
1 | 4
2 | 1
2 | 2
2 | 3
3 | 1
3 | 4
How do I go about retrieving the unique group key for the dimensions 1,3,4 (ie. 1).
