Rules / DAX Expressions

Avoid using the IFERROR function

warning AVOID_USING_THE_IFERROR_FUNCTION · ported · scope: Measure, CalculatedColumn

What it checks

Measures and calculated columns that call IFERROR.

Why it matters

IFERROR makes the engine evaluate the expression row by row so it can catch a failure, which switches off the bulk evaluation that makes DAX fast. Most uses guard a division, and DIVIDE handles that case without the penalty. The rest usually hide a data problem, such as text in a numeric column, that is better fixed in Power Query where the failure cannot happen.

How to fix it

Replace IFERROR([A] / [B], 0) with DIVIDE([A], [B], 0). For type conversions, clean the column in Power Query so the conversion cannot fail. If a guard is unavoidable, test the condition with IF instead of catching the error.

Links

• https://github.com/microsoft/Analysis-Services/blob/master/BestPracticeRules/BPARules.json
• https://www.elegantbi.com/post/top10bestpractices

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