Question 1

for example, we want to update the existing data warehouse (before the data warehouse only contains data 2022-2023) by adding the newer data (data from 2024) from operational database but the newer data have different structure than older data (i.e. more granular), should we change the data warehouse schema?

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This is very good question, which is quite common in the industry.

this process is related to ETL process. (extract. transform, loading)

Regarding your question, you may nee to do some data transformation to transfor data into suitable format used for data warehouse

Moreover, if this new data is updated regularly, the data warehouse will differ, which is called an active data warehouse (data constantly increasing or being updated). Please refer to the textbook if you are interested, but this topic will not be covered in this unit.

This is different from what we learned now (passive data warehouse).