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power bi/flashcards/power-bi-cards-transform

Data import & transformation — flashcards

One card per lesson — 6 in this module. Recall the key points, then check. 6 cards. Click a card to flip, or use the arrow keys and space bar.

  1. How Power BI fits together — what are the key points?

    Power Query shapes data at refresh; DAX calculates at query time · VertiPaq is a compressed columnar store — the model layer · Transform in Power Query, calculate in DAX Read the lesson

  2. Import, DirectQuery and composite models — what are the key points?

    Import = fastest, but bounded by size and refresh cadence · DirectQuery = current data, but every interaction hits the source · Dual mode on dimensions is the standard composite-model pattern Read the lesson

  3. Shaping data in Power Query — what are the key points?

    Every applied step is M code; order changes results and performance · Remove columns and filter rows as early as possible · Query folding pushes work to the source — check View Native Query Read the lesson

  4. The M language — what are the key points?

    M is case sensitive and every query is one let/in expression · each is shorthand for a per-row function; else is mandatory in if · try ... otherwise prevents one bad row from failing a refresh Read the lesson

  5. Navigating Power Query — what are the key points?

    Applied Steps is an editable, ordered transformation script · Query folding pushes work to the source — check with View Native Query · Static values belong in Power Query; anything filter-responsive is a measure Read the lesson

  6. Merging and appending queries — what are the key points?

    Anti joins directly answer which rows have no match · Trim and lowercase both key columns before merging · Prefer a model relationship over a merge where a real relationship exists Read the lesson