Tutorial with example
In this video I will show you how DAX RAND function works and also how to use it to break ties on the RANKX calculation to be able to create TOP X lists in Power BI.
Download example file:
In Power Pivot workbooks, recalculation depends on various factors, including whether the workbook is set to Manual or Automatic recalculation mode, and whether data has been refreshed. This is different from Microsoft Excel, where you can control when RAND generates a new random number by turning off recalculation.
RAND and other volatile functions that do not have fixed values are not always recalculated. For example, execution of a query or filtering will usually not cause such functions to be re-evaluated. However, the results for these functions will be recalculated when the entire column is recalculated. These situations include refresh from an external data source or manual editing of data that causes re-evaluation of formulas that contain these functions.
Moreover, RAND is always recalculated if the function is used in the definition of a measure.
Also, in such contexts the RAND function cannot return a result of zero, to prevent errors such as division by zero.
This DAX function is not supported for use in DirectQuery mode.