TimeSeries: zero then 1000 - strange graph

  • What Grafana version and what operating system are you using?
    debian 11, 10.0.0-preview (package installed)

  • What are you trying to achieve?
    Just a time series…

  • How are you trying to achieve it?
    This is the query:

SELECT
  UNIX_TIMESTAMP(TIMESTAMP) AS "time",
  DEVICE AS metric,
  CONVERT(VALUE, DOUBLE) * -1 as Batterie_Entladung
FROM history
WHERE
  $__timeFilter(TIMESTAMP) AND
  DEVICE = 'sungrow' AND READING = 'Battery_power_discharge'
ORDER BY TIMESTAMP

With this data:

|2023-09-13 20:22:28.000|sungrow|MODBUSATTR|Battery_power_discharge: 0|Battery_power_discharge|0||
|2023-09-14 15:29:30.000|sungrow|MODBUSATTR|Battery_power_discharge: 1931|Battery_power_discharge|1931||
  • What happened?
    Please have a look at the series in light green

  • What did you expect to happen?
    I would think that the light green line would be on zero between the two data points

Maybe this is a configuration issue or is there a possibility to “optimize” the query?
I hope, this question is not already answered, I could not find anything…
Best regards and thanks in advance,
Otto