Daily aggregates via histogram function

InfluxDB 2
,
1

I have some simple time series data, and I’d like to create daily aggregates for the whole of last year via the histogram function, so that for every day I store the count of samples in each histogram bin.

Then I should be able to use the histogramQuantile function to calculate historical quantiles.

I can write the query easily enough to generate the histograms:

from(bucket: "B1")
    |> range(start: 2024-01-01T00:00:00Z, stop: 2025-01-01T00:00:00Z)
    |> window(every: 1d)
    |> histogram(
        bins: [
            0.,
            1.,
            2.,
            3.,
            999.,
        ],

This produces a result set with _start, _stop, _field, _value, and le columns, where _value is the bin count and le is the upper bound of each bin. This is all good.

But when i put this in a task, piped into the to() function to store the data in another bucket, I cannot get it to include the le column.

    |> map(fn: (r) => ({r with _time: r._start}))
    |> to(
        bucket: "B1daily",
        fieldFn: (r) => ({"_value": r._value, "le": r.le}),
        org: "MYORG",
    )

I’ve tried with and without the fieldFn, but whatever do I cannot get le to be stored in my target bucket.

I’m probably missing something simple about how numeric columns work in Influx.