Re: Power BI September 2026 Feature Summary

Lot of great updates here, but unless APPROXIMATEDISTINCTCOUNT in import mode is a precursor update to full HyperLogLog (HLL) support in Vertipaq, I think you missed the point of having approximate distinct count in import mode at all.  If you're going to go to the trouble of importing a key column for counts, why wouldn't you use actual DISTINCTCOUNT?  The benefit of having approximate distinct count (via HLL) support in import mode is that you could significantly reduce the number of rows required and enable dynamic, re-aggregable approximate distinct counts for columns that otherwise cannot fit in-memory by merging the HLL sketches at query time.  Maybe it's a pipe-dream, but simply enabling APPROXIMATEDISTINCTCOUNT for use in import-mode does not help much on data at a very large scale.

Approximate Distinct Count in Import Mode via HyperLogLog (HLL) | Microsoft Fabric Community