PL-300 - Model the Data - Section 2.3

Optimize model performance by reducing cardinality, choosing storage modes, and using aggregations.

Select import, DirectQuery, or dual storage modes and configure aggregations to balance query speed against data freshness. Use Performance Analyzer to identify slow visuals, and apply cardinality reduction and query folding to reduce load on the source system.

storage modesaggregationsquery foldingcardinality reductionPerformance Analyzer

Practice question for this objective

Free sampleModel the Datamedium

Performance Analyzer reports that a card visual spent 1,400 ms in one duration category and only 80 ms elsewhere. The semantic model uses Import storage mode. Which duration category most likely represents the 1,400 ms reading?

  • AThe Direct query category, covering query time against the data source.
  • BThe Visual display category, covering rendering and geocoding work.
  • CThe Other category, covering query preparation and waiting work.
  • DThe DAX query category, covering query time against the semantic model. Correct
DAX query covers semantic-model query time; Direct query only appears for DirectQuery tables. On an Import model, the DAX query duration is the time between the visual sending the query and the semantic model returning results. A long DAX query duration on a simple card almost always points to expensive measure logic or relationship traversal.

Why A is wrong: Direct query only appears when a table uses DirectQuery storage mode; an Import model does not generate a Direct query duration.

Why B is wrong: Visual display covers drawing on screen and retrieving images; a single card with a number rarely spends 1,400 ms in render time.

Why C is wrong: Other covers query preparation and waiting on other visuals; it is rarely the dominant cost for an isolated card.

Why D is correct: Correct. On an Import model, the DAX query duration is the time between the visual sending the query and the semantic model returning results.

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