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power bi/flashcards/power-bi-cards-model

Data modelling & relationships — flashcards

One card per lesson — 5 in this module. Recall the key points, then check. 5 cards. Click a card to flip, or use the arrow keys and space bar.

  1. Star schema and why it matters — what are the key points?

    One fact table, surrounded by one-to-many dimensions · Flatten snowflakes into single wide dimensions in Power Query · A contiguous Date table marked as such is required for time intelligence Read the lesson

  2. Relationships and filter direction — what are the key points?

    Filters flow from the one side to the many side by default · Prefer single direction; use CROSSFILTER in a measure instead of Both · USERELATIONSHIP activates an inactive relationship for one calculation Read the lesson

  3. Measures vs. calculated columns — what are the key points?

    Columns compute at refresh and cost memory; measures compute at query time and cost CPU · Default to measures; add columns only when you must slice by the value · SUMX and friends give row context inside a measure Read the lesson

  4. Active and inactive relationships — what are the key points?

    Only one relationship between two tables can be active · USERELATIONSHIP activates an inactive one inside CALCULATE · Duplicating the date table is the simpler alternative for report authors Read the lesson

  5. Building a calendar table — what are the key points?

    Time intelligence needs a contiguous calendar table with no gaps · Sort month names by a month-number column or they sort alphabetically · Turn off auto date/time and use one proper calendar table Read the lesson