With flux request, how to get the date of the first point and the last point inserted in the bucket?

InfluxDB 2
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1

With flux query, how to get the date of the first point and the last point inserted in the bucket?
thanks.

2

@lepton.phlb

Does this bucket contain hours, days, months or years’ worth of data? Usually a Flux query is applied on a certain time window (e.g. find the first and last points).

3

If I use and imported bucket, for a deferred exploitation of the data, and I don’t know the date of the first point and the last point, I need to send a query to retrieve this time window.

4

@lepton.phlb

OK, got it. Something like this should work for the first point. Change the last 2 lines to get the last point using the last() function.

from(bucket: "HillValley")
  |> range(start: 0, stop: now())
  |> filter(fn: (r) => r["_measurement"] == "ElectricityData")
  |> filter(fn: (r) => r["Location"] == "clocktower")
  |> filter(fn: (r) => r["Source"] == "lightning")
  |> filter(fn: (r) => r["_field"] == "power")
  |> first(column: "_time")
  |> yield(name: "first_point_timestamp")

image
image2154×166 31 KB

5

Great! I hadn’t thought about range(start: 0, stop: now()) and the last 2 lines of your query. Thanks for your reply and your help.

6

It works :slight_smile:
To obtain the first data point date:

from(bucket: "my-bms-timeseries")
  |> range(start: 0, stop: now())
  |> filter(fn: (r) => r["_measurement"] == "BATTERY_1")
  |> filter(fn: (r) => r["0"] == "BRANCH_A")
  |> filter(fn: (r) => r["1"] == "BRANCH_DATA")
  |> filter(fn: (r) => r["_field"] == "BRANCH_CURRENT")
  |> first(column: "_time")
  |> yield(name: "first")

To obtain the last data point date:

from(bucket: "my-bms-timeseries")
  |> range(start: 0, stop: now())
  |> filter(fn: (r) => r["_measurement"] == "BATTERY_1")
  |> filter(fn: (r) => r["0"] == "BRANCH_A")
  |> filter(fn: (r) => r["1"] == "BRANCH_DATA")
  |> filter(fn: (r) => r["_field"] == "BRANCH_CURRENT")
  |> last(column: "_time")
  |> yield(name: "last")
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