Star schema, normalized dimensions, denormalized hierarchy level keys

Question

Given the following star schema tables.

• fact, two dimensions, two measures.

#   geog_abb  time_date amount     value
#1:                


        

Answer 1

You are building a snowflake schema with shortcuts.

It's used and BI tools can easily use the shortcuts.

You can also have shortcuts from a parent level of a dimension to a fact table at child level for that dimension. It works, you can skip a join, but you need to store an additional column in the fact table.

The only concern is about data integrity, if a parent-child relationship changes you need to update not only the child table, but also all other tables where this relationship is stored.

It's not a big deal if you generate every time your dimension table from your normalize data, but you need to be careful, even more if you store a parent ID in the fact table.