PL-300 Prepare the data Practice Question
You are building a Power BI semantic model that combines data from an on-premises SQL Server database and a SharePoint Online list. The SQL Server table contains 10 million rows and updates hourly. The SharePoint list contains 500 rows and updates daily. You need to minimize the data load time and ensure the model refreshes within the scheduled 30-minute window. What should you do?
⚠ Common exam trap
It's easy for candidates to assume Import mode is always best for performance, but for very large tables with frequent updates, DirectQuery avoids the bottleneck of importing millions of rows, while small tables are better imported to avoid live query overhead.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use DirectQuery for the SQL Server table and Import mode for the SharePoint list.
Using DirectQuery for the large SQL Server table (10M rows, hourly updates) avoids importing all rows into the model, significantly reducing data load time and memory usage. Import mode for the small SharePoint list (500 rows, daily updates) is appropriate since it loads quickly and supports full DAX functionality, while the combination keeps the total refresh within the 30-minute window.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use DirectQuery for the SQL Server table and Import mode for the SharePoint list.
Why this is correct
DirectQuery for the SQL Server table is correct because it keeps the 10-million-row table out of the model's memory, avoiding a long and costly import/refresh; queries are pushed to SQL Server at report time. The SharePoint list, which is small, is well-suited to Import mode because SharePoint Online does not support DirectQuery, and importing it enables fast, in-memory performance and full modeling capabilities like calculated columns and relationships.
- ✗
Set both tables to DirectQuery mode.
Why it's wrong here
Setting both tables to DirectQuery mode is invalid because SharePoint Online lists cannot be used with DirectQuery—Power Query for SharePoint Online only supports Import mode. Even if it were technically possible, mixing two DirectQuery sources in one model would create cross-source join limitations, require all relationships to be single-direction, and can cause poor report performance if the SharePoint list is large, but the fundamental blocker is the lack of DirectQuery support for SharePoint.
- ✗
Set the SQL Server table to Dual mode and the SharePoint list to Import mode.
Why it's wrong here
Dual mode for the SQL Server table does not solve the refresh-time problem because Dual mode still imports data into memory to serve as a cache; it merely also allows DirectQuery. The import step would still load 10 million rows and exceed the refresh window, and Dual mode adds unnecessary overhead and model complexity. Since the SharePoint list must be Import mode anyway, there is no benefit to Dual over pure DirectQuery for the SQL Server table.
- ✗
Import both tables into the model and disable incremental refresh.
Why it's wrong here
Importing both tables and disabling incremental refresh would force a full model refresh of 10 million rows every time, which is slow, memory-intensive, and almost certainly exceeds the refresh window. Disabling incremental refresh is especially harmful because it removes the only mechanism that could partition the large table into manageable ranges. Additionally, the 10-million-row table would consume significant RAM, degrading model performance and increasing storage costs, whereas a DirectQuery approach avoids this entirely.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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