Abstract: A system for precise quantile determination derives a maximum relative error value ? that guarantees that an exact result for every quantile can be determined in no more than two passes. The system computes a quantile summary of the datapoints, that specifies lower and upper bounds of the quantile ranks for selected datapoints, and determines for each quantile rank, the lower and upper bounds for values between which the quantile must occur. The system filters out in a second pass those datapoints that are not within the bounds to provide subsets; and computes from the quantile ranks and the subsets, the precise quantiles.

Abstract: A system for precise quantile determination derives a maximum relative error value ? that guarantees that an exact result for every quantile can be determined in no more than two passes. The system computes a quantile summary of the datapoints, that specifies lower and upper bounds of the quantile ranks for selected datapoints, and determines for each quantile rank, the lower and upper bounds for values between which the quantile must occur. The system filters out in a second pass those datapoints that are not within the bounds to provide subsets; and computes from the quantile ranks and the subsets, the precise quantiles.