Want to transform one counter to incremental

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1

Hi,

I use TIG that way:

  • Telegraf pools one SNMP objet on a network device (the ifInUcastPkts object)(Interface Input Unicast Packet counter))
  • Telegraf sends the result to InfluxDB
    -Grafane is used to show the object as a chart

But the object is a counter and I would like to graph only the delta value.
Example:
records:
400
400
400
405
405
410
415

What I try to get:
0
0
0
5
0
5
5

I try to add a transfrom instance to my grafana’s resuest, but impossible to get up to the goal…

Can somebody helps me ?

  • What Grafana version and what operating system are you using?
    v10.0.0 under Unbuntu

  • What are you trying to achieve?
    use a transform instance to change one field from absolute counter to delta

  • How are you trying to achieve it?
    adding a transform instance to a query request

  • What happened?
    every thing except the expected result

  • What did you expect to happen?
    transform one absolute field in a delta field (=current record - previous record)

  • Can you copy/paste the configuration(s) that you are having problems with?
    Here is the query request:
    from(bucket: “telegraf”)
    |> range(start: 2023-06-14T07:23:40.969Z, stop: 2023-06-14T13:23:40.969Z)
    |> filter(fn: (r) => r[“_measurement”] == “snmp”)
    |> filter(fn: (r) => r[“FW1”] == “192.168.19.156”)
    |> filter(fn: (r) => r[“_field”] == “ifInUcastPkts”)
    |> aggregateWindow(every: 15s, fn: mean, createEmpty: false)
    |> yield(name: “mean”)

  • Did you receive any errors in the Grafana UI or in related logs? If so, please tell us exactly what they were.
    no

  • Did you follow any online instructions? If so, what is the URL?
    yes (a load of web sites) and no (as I din’t find any help)