pbiplintRules / Performance
Do not use floating point data types
What it checks
Columns of any kind whose data type is Double, which Power BI Desktop calls Decimal Number.
Why it matters
Double is binary floating point, so values like 0.1 have no exact representation and sums drift in the last digits. Two totals that should match can differ by a fraction of a cent, and a money column stored as Double compresses worse than the same values as Fixed Decimal Number, so it costs memory as well. Fixed Decimal Number stores four decimal places exactly, and Whole Number compresses best of all.
How to fix it
In Power Query, change the column type to Fixed Decimal Number or Whole Number so the conversion happens before load. Changing it in the model view works too. In the TMDL file the property is dataType: decimal or dataType: int64. Keep Double only for values that need more than four decimal places, such as scientific measurements.