Q2: What if you have to merge, add, or delete columns or add new dimensions later?
Can that be done easily?
Answer:
Yes, it can be done, but it requires careful planning depending on where the change happens. If we need to add a new dimension attribute (like adding a "Customer Credit Score" column to Dim_Customer), it is very easy—
- we just alter the dimension table
- and update our ETL script for future loads.
If we need to change how a fact table is structured or completely delete a core metric, we have to rewrite the ETL logic and sometimes reprocess or reload historical data so that old reports do not break or show incorrect math.
