Optimize Model Performance PL-300 Practice Questions (Page 5)

Questions 21–25

1. 21foundation · easy

   Which of the following is a common method to analyze the performance of a DAX query in Power BI?

   • AUse the Query Editor to view the query plan.
   • BUse the Relationship view to identify slow queries.
   • CUse the Data Profiling tool to measure query speed.
   • DUse Performance Analyzer to view the DAX query and its duration.
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2. 22application · medium

   A report page contains a matrix visual that displays sales by region and product category. Users report that the page takes a long time to load. You open Performance Analyzer and see that the matrix visual's DAX query has a duration of 8 seconds, while other visuals on the page complete in under 1 second. What should you do first to diagnose the bottleneck?

   • AReplace the matrix visual with a table visual to see if the problem is visual-specific.
   • BIncrease the 'Cache data for this visual' setting in the visual's properties.
   • CExpand the DAX query in Performance Analyzer to view the query text and execution statistics.
   • DDisable the matrix visual's totals and subtotals to reduce the number of rows returned.
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4. 23application · medium

   A company's Power BI dataset imports a fact table with 5 years of transactional history. The report only needs to show the current fiscal year and the previous fiscal year. The table also includes a 'BatchID' column used only for data-loading audits. The model refresh takes too long and the report is sluggish. What should you do to improve performance with the least impact on report functionality?

   • AFilter the fact table to the current and previous fiscal year during import, and remove the 'BatchID' column from the model.
   • BDisable auto date/time and keep the 'BatchID' column for future auditing.
   • CKeep all rows but remove the 'BatchID' column and create a calculated table for the two fiscal years.
   • DUse a row-level security (RLS) filter to limit data to the current and previous fiscal year for all users.
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5. 24application · medium

   A report page contains a matrix visual that displays sales by region and product. Users report the page is slow to render. You open Performance Analyzer and see that the matrix visual takes 8 seconds, with 7.5 seconds spent in the DAX query. What should you do next to diagnose the bottleneck?

   • AExamine the DAX query generated for the visual to identify which measures and columns are being evaluated.
   • BReplace the matrix visual with a card visual to reduce the number of columns.
   • CDisable the Performance Analyzer to speed up the visual rendering.
   • DIncrease the number of rows returned by the visual to see if the performance improves.
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6. 25expert · hard

   A logistics company has a Power BI model that imports GPS data every 10 seconds for each vehicle. The report needs to show daily distance traveled per vehicle and per route. The model is too large and refresh takes too long. The company also needs to keep the raw data for future analysis. What should the developer do to balance performance and data retention?

   • AKeep the raw data and use a measure to calculate daily distance, but remove the 'Route' column to reduce size.
   • BAggregate the GPS data to daily distance per vehicle and route and remove the raw data from the model.
   • CCreate two tables: one aggregated to daily distance per vehicle and route for the report, and one with raw data that is not used in the report.
   • DUse a row-level security (RLS) rule to limit the raw data to the current day for all users.
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