InfluxDb downsampled data

Add-ons Persistence Services
1

I’m considering the move to InfluxDb (v1) from RR4J. I currently make use of charts, in the main UI and sitemaps, and analytics. I want to retain the RR4J functionality of downsampling historical data, but ideally I want to gain more control over this (e.g. temperature data I don’t need to retain granular information very long, where other measurements I have a desire to keep as-is).

As I understand it, this can be easily achieved with InfluxDb 1 through the use of retention policies and continuous queries to manage downsampling of measures.

What I can’t work out though is how openHAB is able to access historical data. Is there a naming convention or other concept that enables openHAB to access downsampled data points?

2

Maybe Influx V2 is something for you then. There, you can set the retention period and create downsampling rules.

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import "timezone"
import "date"

option task = {name: "Einspeisung", every: 1d}

option location = timezone.location(name: "Europe/Berlin")

from(bucket: "openHAB")
    |> range(start: date.add(d: -1d, to: today()), stop: date.truncate(t: today(), unit: 1d))
    |> filter(fn: (r) => r["_measurement"] == "Einspeisung_kWh")
    |> filter(fn: (r) => r._field == "value")
    |> aggregateWindow(every: 1d, fn: last, createEmpty: false)
    |> to(bucket: "openHAB_history")

In this case, the downsampled data in the second bucket cannot be accessed directly from openHAB. But with a scipt:

#!/bin/bash

curl -s -X POST “http://192.168.178.26:8087/api/v2/query?org=my_organisation” 
-H “Authorization: Token 7topsecrettoken==” 
-H “Content-Type: application/vnd.flux” 
–data ’
from(bucket:“openHAB_history”)
|> range(start: -365d)
|> filter(fn:(r)=>
r[“item”] == “Gaszaehlerstand” or
r[“item”] == “Stromzaehler_kWh” or
)
|> filter(fn:(r)=> r[“_field”] == “value”)
|> difference(nonNegative: true)
|> sum()
|> group(columns: [“item”])
|> keep(columns: [“item”,“_value”])
’