Documentation

Comparing values from different buckets

This example uses NOAA water sample data.

This example compares the value from the latest point to an average value stored in another bucket. This is useful when using the average value to calculate a threshold check.

The following query:

  • Uses range() to define a time range.
  • Gets the last value in the means bucket and compares it to the last value in the noaa bucket using last().
  • Uses join() to combine the results
  • Uses map() to calculate the differences
means = from(bucket: "weekly_means")
    |> range(start: 2019-09-01T00:00:00Z)
    |> last()
    |> keep(columns: ["_value", "location"])

latest = from(bucket: "noaa")
    |> range(start: 2019-09-01T00:00:00Z)
    |> filter(fn: (r) => r._measurement == "average_temperature")
    |> last()
    |> keep(columns: ["_value", "location"])

join(tables: {mean: means, reading: latest}, on: ["location"])
    |> map(fn: (r) => ({r with deviation: r._value_reading - r._value_mean}))

Example results

location_value_mean_value_readingdeviation
coyote_creek79.82710622710623899.172893772893772
santa_monica80.20451339915374854.79548660084626

Was this page helpful?

Thank you for your feedback!


The future of Flux

Flux is going into maintenance mode. You can continue using it as you currently are without any changes to your code.

Flux is going into maintenance mode and will not be supported in InfluxDB 3.0. This was a decision based on the broad demand for SQL and the continued growth and adoption of InfluxQL. We are continuing to support Flux for users in 1.x and 2.x so you can continue using it with no changes to your code. If you are interested in transitioning to InfluxDB 3.0 and want to future-proof your code, we suggest using InfluxQL.

For information about the future of Flux, see the following: