PL-300 Question 111

Community Discussion

Written by other learners. Comments can disagree with the marked answer — check the official documentation when in doubt.

• Chose B1

  Concatenating two high-cardinality columns like IoT GUID and IoT ID into a new column does not reduce cardinality — it just creates another unique value per row, which still consumes a lot of memory and compresses poorly in Power BI’s in-memory engine. You’re essentially replacing two large columns with one equally large column. This does not help performance, and may even make it worse if the new column is used in visuals or relationships.

• 1

  I believe the question is ambiguous and both answers are correct. On one hand, reducing the number of columns in the model can improve performance. On the other hand, storing the 'IoT ID' field as text (concatenated with the 'IoT GUID' field) can negatively impact the model's performance in queries that require filtering by that field. Additionally, performing this concatenation can break necessary relationships with the 'IoT ID' field. Therefore, performing the suggested concatenation seems like a bad idea from a general standpoint. However, if we strictly adhere to the requirement ('You need to analyze IoT events by the hour and day of the year. The solution must improve dataset performance.') and ignore other negative consequences, I personally conclude that A is the correct answer, the proposed solution will improve the dataset performance

• Chose A2

  Resulting column would not improve the analysis but it would reduce the size of the data model as one column would be removed so it should improve performance