Iterator nested inside another iterator
"Iterator nested inside another iterator" is one of the performance checks Auditabi runs on a Power BI semantic model. n expression(s) run SUMX / AVERAGEX / FILTER inside another iterator. It is a medium-severity finding: the model still works, but results are wrong in some filter contexts, slow, or fragile under change. Pre-aggregate the inner result in a variable outside the outer iterator, or restructure with SUMMARIZE / CALCULATE so each table is scanned once.
What is detected
n expression(s) run SUMX / AVERAGEX / FILTER inside another iterator. Cost grows with the product of the two row counts.
Why it matters
Wrong in some filter contexts, slow, or fragile under change. Fix in the next iteration.
How to fix it
Pre-aggregate the inner result in a variable outside the outer iterator, or restructure with SUMMARIZE / CALCULATE so each table is scanned once.
Reference
SQLBI: Optimizing nested iterators in DAX
Does your model fail this check?
Free static audit with the exact objects, no account, nothing stored.
More DAX checks
- Arithmetic or comparison on a measure that returns text
- Measure returning text in one branch and a number in another
- Share denominator clears a fact-table column instead of the dimension
- "Previous period" window overlaps the current one
- Percentage label built without ×100
- Percentages and amounts summed together