This function is preview. It is currently not supported by Microsoft Support. For additional limitations, see Remarks.

Returns the approximate number of rows that contain distinct values in a column. This function can query large amounts of data with potentially better performance than DISTINCTCOUNT, with slight deviation from the exact result.




Term Description
column The column that contains the values to be counted. This cannot be an expression.

Return value

The approximate number of distinct values in column.


The only argument to this function is a column. You can use columns containing any type of data. When the function finds no rows to count, it returns a BLANK, otherwise it returns the count of distinct values.

This function is preview. The following limitations apply:

  • This function currently supports DirectQuery connections only to the following data sources:

    • Azure SQL Database
    • Azure SQL Data Warehouse
  • This feature is not yet available in Intellisense.