bottomk Metrics Operator

The bottomk operator applies a specified aggregation function to the time series that match the query selector, and returns the n time series that have the lowest evaluated value over the query time range.  

Syntax

bottomk (N, SCALAR_EXPRESSION) [by FIELD [, FIELD, ...]]

Where: 

N is the number of time series to chart

SCALAR_EXPRESSION is one these functions:

Function	Description
min	Rank matching time series by which had the minimum value of the metric across the time range, and return the bottom n time series.
max	Rank matching time series by which had the maximum value of the metric across the time range, and return the bottom n time series.
avg	Rank matching time series by the average value of the metric across the time range, and return the bottom n time series.
count	Rank matching time series by the count of the metric values across the time range, and return the  bottom n time series.
sum	Rank matching time series by the sum of the metric values across the time range, and return the bottom n time series.
pct(n)	Return the n time series for which the calculated percentile of the metric values across the time range was lowest, and return the bottom n.
latest	Rank matching time series by the value of the most recently ingested data point, and return the bottom n time series.

Examples

Bottom time series by avg value

This query ranks the time series that match the query selector by the average value of the CPU_Sys metric over the time range, and returns the bottom 5 time series.

_contentType=HostMetrics metric=CPU_Sys | bottomk (5, avg)

The 5 time series with the lowest 99% confidence interval

This query applies a math expression to each time series that match the query selector. The math expression calculates the average value over the time range, plus 3 standard deviations.  The time series are ranked by the calculated value, and the bottom 5 time series are returned.

_contentType=HostMetrics metric=CPU_Sys | bottomk (5, avg + 3 * stddev)

Bottom time series by specified percentile

This query calculates 10th percentile of the  Mem_FreePercent metric for each time series that match the query, ranks the time series on that basis, and returns the bottom 5 time series. 

_contentType=HostMetrics metric=Mem_FreePercent | bottomk (5, pct (10))