Sum of maxima (or absolute difference for incremental measurement)

InfluxDB 2
1

Hello there,
A measurement represents the increasing amount of energy “consumed” by an electric car:

from(bucket: "home_assistant")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["entity_id"] == "evcc_charged_energy_self_kwh")
  |> filter(fn: (r) => r["_field"] == "value")
  |> aggregateWindow(every: v.windowPeriod, fn: last, createEmpty: false)
  |> yield(name: "last")

The measurement of consumed energy amount increases over time but is reset to 0 from time to time (on system restart).

How do I best calculate the total amount of energy consumed between two datetimes (e.g. yesterday or full last year)?

Thanks!

2

Writing my question here helped me to understand the question better myself. This does the job perfectly:

from(bucket: "home_assistant_awf1877")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["entity_id"] == "evcc_charged_energy_self_kwh")
  |> filter(fn: (r) => r["_field"] == "value")
  |> difference(nonNegative: true)
  |> sum()
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