How to compute index numbers at top speed

This article presents different techniques to compute a rownumber column in DAX based on a specific ranking, comparing slow and optimized approaches.

In several data models, you need to assign an index number to a row. The index is an incremental number that sorts the rows according to some rule. For example, you might want to assign an index to sales, so to be able to find the first or the second of a given customer. In this article, we analyze a naïve approach, which turns to be very slow, and an optimized one, using the RANKX function.

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