irate_left()

Calculate the instantaneous rate of change at the left, or earliest, edge of a gauge aggregate

Early access Since 1.6.0

Calculate the instantaneous rate of change at the left, or earliest, edge of a gauge aggregate. This is equal to the second value minus the first value, divided by the time lapse between the two points. This calculation is useful for fast-moving gauges.

Samples

Get the instantaneous rate of change at the start of each 15-minute gauge aggregate.

SELECT
    id,
    bucket,
    irate_left(summary)
FROM (
    SELECT
        id,
        time_bucket('15 min'::interval, ts) AS bucket,
        gauge_agg(ts, val) AS summary
    FROM foo
    GROUP BY id, time_bucket('15 min'::interval, ts)
) t

Arguments

The syntax is:

irate_left(
  summary GaugeSummary
) RETURNS DOUBLE PRECISION

Name	Type	Default	Required	Description
summary	GaugeSummary	-	✔	A gauge aggregate created using gauge_agg

Returns

Column	Type	Description
irate_left	DOUBLE PRECISION	The instantaneous rate of change at the left, or earliest, edge of the gauge aggregate