Computes the approximate median from all row values in a column or group. Input column can be of Integer or Decimal. 
pivot
transform, the function is computed for each instance of the value specified in the group
parameter. See Pivot Transform.The approximate percentile functions utilize a different algorithm for efficiently estimating quantiles for streaming and distributed processing, depending on the running environment where the function is computed.
Tip: Approximation functions are suitable for larger datasets. As the number of rows increases, accuracy and calculation performance improves for these functions. 
approximatemedian(myRating) 
Output: Returns the approximate median of the values in the myRating
column.
approximatemedian(function_col_ref) [group:group_col_ref] [limit:limit_count] 
Argument  Required?  Data Type  Description 

function_col_ref  Y  string  Name of column to which to apply the function 
dec_error_bound  N  decimal  Error factor for computing approximations. Decimal value represents error factor as a percentage (0.4 is 0.4%). 
For more information on the group
and limit
parameters, see Pivot Transform.
Name of the column the values of which you want to calculate the median. Column must contain Integer or Decimal values.
Required?  Data Type  Example Value 

Yes  String (column reference)  myValues 
As needed, you can insert an error boundary factor as a parameter into the computation of this approximate value.
NOTE: This value is not applicable to jobs executed on the running environment. 
0.5
(0.5%). Required?  Data Type  Example Value 

No  Decimal (literal)  0.01
