LN() in Query always returns nothing ?!

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1

Hi There,

ATM I try to create a query which calculates the dew point from Temp C° and Absolute Humidity.
I found the correct formula, but I’m unable to translate it properly to Influxlang

I know, the formula is not finished yet, but as soon as I use any math functions like LOG() or LN() I get null returns.

this query without LN()

SELECT (mean(“Wohnzimmer_AbsoluteHumidity”)) FROM “exec_netatmo” WHERE timeFilter GROUP BY time(__interval) fill(previous)

returns

|2019-04-18 10:29:20|7.92|
|2019-04-18 10:29:00|7.92|
|2019-04-18 10:28:40|7.88|
|2019-04-18 10:28:20|7.88|
…

But this equal query with LN() returns absolutely nothing.

SELECT LN(mean(“Wohnzimmer_AbsoluteHumidity”)) FROM “exec_netatmo” WHERE timeFilter GROUP BY time(__interval) fill(previous)

Where is my syntax mistake ??!

I’m using InfluxDB 1.6 on a LXC Container with Ubuntu 16
and latest Grafana as front-end in Docker container.

2

… forget it. I found out on this system was a version 1.5.x installed. As seen in documentation LN() needs at least version 1.6.
Server has been upgraded to latest 1.7. Now it works :slight_smile:

3

Awesome. Glad you got it sorted, @blue_focus :+1: