percentilekll

This section contains reference documentation for the PERCENTILEKLL function.

KLL Sketch is an approxiamate quantiles algorithm which targets optimal space for a given accuracy. PERCENTILEKLL is a percentile calculation aggregation function based on Apache Datasketches KLL Doubles Sketch implementation.

Pinot also offers a 'raw' variant, PERCENTILEKLLRAW, which returns the serialized sketch that can be used for calculating 'rank' or 'histogram'.

All of the variants of PercentileKLL also support raw sketches in Pinot columns. This means you can create KLL Doubles sketches outside of Pinot and ingest them into columns as binary strings. PercentileKLL will identify these columns merge them to produce aggregate results.

Signature

PercentileKLL(column, percentile, kValue) -> Double

column (required): Name of the column to aggregate on. If the column is a multi value column, use PERCENTILEKLLMV variant.
percentile (required): Percentile value to be calculated [0..100]
kValue: Integer value which determines the size of the sketch. Default value is 200 which corresponds to a normalized rank error of about 1.65%. For details, see the accuracy vs size chart.

Usage Examples

select percentileKLL(ArrDelayMinutes, 90) as DelayP90
from airlineStats

DelayP90

select Carrier, percentileKll(ArrDelay, 50, 600) as MedianDelay
from airlineStats
where ArrDelay > 0
group by Carrier
order by 2 desc
limit 3

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