PL-300 Prepare the data Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Create aggregations on the fact table.

  Why this is correct

  Creating aggregations on the fact table pre-summarizes data at higher grain levels (e.g., month, category), allowing the Import storage engine to serve queries from a smaller cached table set. Because Power BI's VertiPaq columnar compression and in-memory technology can scan aggregation tables far faster than the full transaction-level fact table, this directly reduces query response time. This is the correct answer because aggregations are a proven, first-class performance feature in Import mode, not merely a side effect of refresh or schema changes.

• ✗

  Increase the scheduled refresh frequency.

  Why it's wrong here

  Increasing scheduled refresh frequency controls how often the dataset is refreshed from the source, but it has no effect on how queries are executed or how quickly the in-memory model responds. A more frequent refresh merely keeps data more current; it does not reduce the cardinality of the fact table, change storage compression, or add pre-aggregated summaries. In fact, more frequent refreshes can temporarily consume CPU and memory, but they never improve the speed of individual analytical queries against the cached data.

• ✗

  Reduce the number of dimension tables.

  Why it's wrong here

  Reducing the number of dimension tables is not a valid performance optimization because it would break the star schema relationships and lose the ability to filter or group by meaningful business attributes. In Power BI Import mode, query performance is primarily driven by the size of the fact table and the cardinality of columns, not by the count of dimension tables. Removing dimension tables would require denormalizing attributes into the fact table, which increases row width and storage, potentially degrading performance further rather than improving it.

• ✗

  Enable 'Load to report' for all tables.

  Why it's wrong here

  Enabling 'Load to report' for all tables simply makes every table visible to report authors in the Fields pane; it does not alter how data is stored, compressed, or queried. In Import mode, all tables in the dataset are already loaded into memory regardless of whether the 'Load to report' checkbox is selected. This setting only affects the report authoring experience (e.g., preventing a table from appearing as a standalone entity), so it has zero impact on DAX query execution speed or aggregation behavior.

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