idelta_left()

Since 1.3.0

Calculate the instantaneous change at the left, or earliest, edge of a counter aggregate. This is equal to the second value minus the first value, after accounting for resets.

Samples

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

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

Arguments

The syntax is:

idelta_left(
  summary CounterSummary
) RETURNS DOUBLE PRECISION

Name	Type	Default	Required	Description
summary	CounterSummary	-	✔	A counter aggregate created using counter_agg

Returns

Column	Type	Description
idelta_left	DOUBLE PRECISION	The instantaneous delta at the left, or earliest, edge of the counter aggregate