Power BI Data Modeling Flashcards
6 cards from real Microsoft Power BI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Power BI Data Modeling flashcards as text
In Power BI, what is a 'calculated column' and when is it evaluated?
Answer: A DAX column added to a table, evaluated at data refresh/load time
A calculated column is defined using DAX and is computed and stored in the model at data refresh or load time.
What is a 'snowflake schema' in Power BI?
Answer: A star schema where dimension tables are further normalized into sub-tables
A snowflake schema extends a star schema by normalizing dimension tables into multiple related sub-dimension tables.
When should you use a 'measure' instead of a 'calculated column' in Power BI?
Answer: When the calculation aggregates data dynamically based on filter context
Measures are best for dynamic aggregations that change based on the current filter or row context at query time.
What happens to model performance if you have too many calculated columns in a large Power BI dataset?
Answer: Dataset file size increases and refresh times slow down
Each calculated column adds to the in-memory storage of the model, increasing file size and potentially slowing refresh times.
What is the purpose of a 'date table' in a Power BI data model?
Answer: To enable time intelligence DAX functions to work correctly
A properly configured date table is required for DAX time intelligence functions like TOTALYTD and SAMEPERIODLASTYEAR to work correctly.
How do you mark a table as a 'Date Table' in Power BI Desktop?
Answer: In Model View, select Mark as Date Table from the table's context menu
You right-click the table in Model View (or use the Table tools ribbon) and select 'Mark as date table' to designate it as the official date table.