This function calculates the given quantile value per group. QUANTILE can be applied to INT, FLOAT or DATE columns.
The quantile parameter passed to this function has to be an expression that results in a constant float number between 0 (same as MIN) and 1.0 (same as MAX).
To calculate a quantile value for a group, we first sort all values of this group and calculate the index at which the quantile value is located. The value at this index is then returned. If the calculated index is a decimal number (e.g., 1.5), it is rounded up. For example, suppose you want to calculate the 0.25 quantile for the following group: [ 1 , 3 , 3 , 4 , 4 , 5 ]. The calculated index in this case is 1.5, which means that the final quantile value cannot be clearly determined. We therefore round the calculated index up to 2 and return 3 as the final quantile value for this group.