MQTT - parsing / topic problem

Telegraf
1

i am reading data from a microcontroller
home/room/workshop/temperature1 20.36
home/room/workshop/humidity 46.36
home/room/workshop/pressure 996.27
home/room/workshop/temperature2 16.94

i read in this data with telegraf
telegraf.conf
…
[[inputs.mqtt_consumer]]
…
topics = [
“home/+/+/+”,
]
…
data_format = “value”
data_type = “float”

and
[[inputs.mqtt_consumer.topic_parsing]]
topic = “home/+/+/+”
measurement = “measurement///"
tags = "/location1/location2/field”
#fields = “//_/test”

## Value supported is int, float, unit

# [[inputs.mqtt_consumer.topic.types]]

key = float

[[processors.pivot]]
tag_key = “field”
value_key = “value”

output from the log file

home,location1=room,location2=workshop,topic=home/room/workshop/temperature2 temperature2=16.88 1678815798606918574

my problem is now, the issue of topic=… since this is also written to the database

A solution is to leave out the topic area [[inputs.mqtt_consumer.topic_parsing]], but then telegraf no longer starts.
2023-03-14T17:53:25Z E! [telegraf] Error running agent: could not initialize input inputs.mqtt_consumer: config error topic parsing: measurement length does not equal topic length
the database entry
Table: keys: [_start, _stop, _field, _measurement, location1, location2, topic]
_start:time _stop:time _field:string _measurement:string location1:string location2:string topic:string _time:time _value:float

2023-03-14T17:27:59.732326779Z 2023-03-14T17:57:59.732326779Z temperature1 home room workshop home/room/workshop/temperature1 2023-03-14T17:31:18.550720212Z 20.19

I don’t know how I don’t get this entry topic= transferred to the database
Tanks

2

Your topic parsing section is screwed… Every element there has to have the same (topic-length) number of elements e.g.

[[inputs.mqtt_consumer.topic_parsing]]
  topic = "home/+/+/+"
  measurement = "/measurement/_/_/_"
  tags = "/_/location1/location2/field"
3

Hi,
I don’t understand the hint.
My topic from controller is:
home/room/workshop/temperature1 23.02
home/room/workshop/humidity 37.63
home/room/workshop/pressure 1012.33
home/room/workshop/temperature2 19.06

I have four entries
home measurement
room location1
workshop location2
temperature1 field

[[inputs.mqtt_consumer.topic_parsing]]
topic = “home/+/+/+”
measurement = “measurement///"
tags = "/location1/location2/field”
#fields = “//_/field”

The entry in the database is:
Table: keys: [_start, _stop, _field, _measurement, location1, location2, topic]
_start:time _stop:time _field:string _measurement:string location1:string location2:string topic:string _time:time _value:float

2023-03-15T13:15:07.861256140Z 2023-03-15T13:25:07.861256140Z temperature2 home room workshop home/room/workshop/temperature2 2023-03-15T13:24:48.356193692Z 19.31

It doesn’t look bad, but the topic entry shouldn’t be there.
I can’t get rid of this entry with telegraf.

4

I tested a little.
The configuration works fine, but the “topic” entry in the database doesn’t have to be.

[[inputs.mqtt_consumer.topic_parsing]]
topic = “home/+/+/+”
measurement = “measurement///"
tags = "/location1/location2/field”
#fields = “//_/field”

[[processors.pivot]]
tag_key = “field”
value_key = “value”

It just takes up space.
If someone else has an idea, that would be nice, otherwise I’ll write a program.

2023-03-17T16:40:57.273213356Z 2023-03-17T16:50:57.273213356Z temperature2 home room workshop home/room/workshop/temperature2 2023-03-17T16:50:32.177384182Z 19.31

Note: the description “MQTT Consumer Telegraf Input Plugin” does not work

example
…
[[inputs.mqtt_consumer]]
…
topics = “/sensors/#”
[[inputs.mqtt_consumer.topic_parsing]]
measurement = “/measurement////”
tags = “/_/site/version/device_name/field”
[[processors.pivot]]
tag_key = “field”
value_key = “value”

greetings

5

@Heinz the topic takes up exactly one time the byte size of the topic text for InfluxDB, but you can get rid of it using metric modifiers more specifically tagexclude.

6

Thanks for the info.
I wasn’t at home and will try it now.

7

Hello,
i have some problems with the syntax.
tagexclude = [“home”] doesn’t work that way
my solution is:
[[inputs.mqtt_consumer]]
…

Topics that will be subscribed to.

 topics = [
     "home/#"
 ]

…
data_format = “value”
data_type = “float”
topic_tag = “”

now the topic is no longer stored in the database.
_start:time _stop:time _field:string _measurement:string location1:string location2:string _time:time _value:float

2023-04-12T08:27:32.087611861Z temperature2 home room workshop 2023-04-12T08:28:11.393511938Z 10.69
2023-04-12T08:27:32.087611861Z temperature2 home room workshop 2023-04-12T08:29:11.396965350Z 10.75

I don’t know if it’s the best solution, but this is how it works

8

Well it would be tagexclude = ["topic"] as the tag is named topic…