Where does SQL stop and data modelling in Power BI start?

Question

I am creating a dataset In Power BI Desktop using data in a SQL Server database. I have read the sqlbi article that recommends using database views but I would like to know: how do I structure them?

There is already a view of the database that contains most of the information I need. This view consists of 7 or 8 other, more basic views (mainly 2 column tables with keys and values), combined using left joins. Do I import the larger view as a flat table, or each of the smaller views and create a relationships etc, ideally in a star schema, in Power BI?

I guess conceptually I am asking: where does the SQL stop and Power BI start when it comes to creating and importing views?

Answer 1

where does the SQL stop and Power BI start when it comes to creating and importing views?

Great question. No simple answer. Typically modeling in Power BI is quicker and easier than modeling in the database. But modeling in the database enables DirectQuery, and is more useful outside of Power BI.

Sometimes it boils down to who is creating the model. The "data warehouse" team will tend to create models in the database first, either with views or tables. Analysts and end-users tend to create models directly in Power BI.

Sometimes it boils down to whether the model is intended to be used in multiple reports or not.

Answer 2

There is no one-size-fits-all approach here.

If your larger view already has what you need and you need it for just one-off report then you can modify it to add additional fields(data points) considering the trade off for effort needed to create a schema.

The decision weather you should import smaller views and connect them as Star schema ( considering that they have a fact table surrounded by dimension tables) depends on if you are going to use that in lot of other reports where the data is connected ie giving you same level of information in every report.

Creating views also depends on lot of other factors, are you querying a reporting snapshot(or read-replicas) of your prod database or you are querying the actual production database. This might restrict you or impact the choice for Views and Materialized Views.