SHOW TAG VALUES shows no records

InfluxDB 1 InfluxQL
, ,
1

Hi! I have a problem with SHOW TAG VALUES which shows no records :disappointed:
My data looks like this

> show series
key
---
mqtt_consumer,host=ploter,topic=tele/temp1/SENSOR
mqtt_consumer,host=ploter,topic=tele/temp2/SENSOR
> show measurements
name: measurements
name
----
mqtt_consumer
> select * from mqtt_consumer
name: mqtt_consumer
time                AM2301_DewPoint AM2301_Humidity AM2301_Temperature host   topic
----                --------------- --------------- ------------------ ----   -----
1642969842839118371 10.3            45.7            22.6               ploter tele/temp2/SENSOR
1642969845438157479 10.9            43.4            24.1               ploter tele/temp1/SENSOR
1642969852853777919 10.3            45.7            22.6               ploter tele/temp2/SENSOR
1642969855449937226 10.7            43.3            24                 ploter tele/temp1/SENSOR
> show tag keys
name: mqtt_consumer
tagKey
------
host
topic
> show tag values with key = "topic"
NOTHING :(
> show tag values with key = "host"
NOTHING :(

My config is

[global_tags]
[agent]
  interval = "10s"
  round_interval = true
  metric_batch_size = 1000
  metric_buffer_limit = 10000
  collection_jitter = "0s"
  flush_interval = "10s"
  flush_jitter = "0s"
  precision = ""
  debug = true
  quiet = false
  logtarget = "file"
  logfile = "/var/log/telegraf/logfile"
  logfile_rotation_max_size = "10MB"
  hostname = ""
  omit_hostname = false
[[outputs.influxdb]]
  urls = ["http://127.0.0.1:8086"]
  database = "sensors"
  username = "xxx"
  password = "xxx"
[[outputs.file]]
  files = ["stdout", "/tmp/metrics.out"]
[[inputs.mqtt_consumer]]
  servers = ["tcp://127.0.0.1:1883"]
  topics = ["tele/+/SENSOR"]
  data_format = "json"

Generaly I have problem with Grafana dashboard.
When I create new panel and start adding new query when I click ā€œ+ā€ button after WHERE clause I can choose a KEY (host/topic) but when I am trying to point specific topic (select tag value) i have noting but ā€œNo options foundā€ on the list.
In a moment of selecting specific topic, Grafana sends below query to InfluxDB http connector

"GET /query?db=sensors&epoch=ms&q=SHOW+TAG+VALUES+FROM+%22mqtt_consum
er%22+WITH+KEY+%3D+%22topic%22 HTTP/1.1" 200 57 "-" "Grafana/8.3.4" fa0444dd-7c89-11ec-8287-000000000000 1204

And it gets empty response (the same as my manual influx query above)

When I cannot select topic, I canā€™t distinguish between sensors and I have all temperature measurement in one series of data (I want to plot every temperature sensor separatly).

The fun thing is, that where I manually prepare query in Grafana, it is working fine (data is returned by influxdb datasource)
SELECT mean("AM2301_Humidity") FROM "mqtt_consumer" WHERE topic = 'tele/temp1/SENSOR' AND $timeFilter GROUP BY time($__interval) fill(null)
A spent whole weekend to figure it out but without luck :disappointed:

HOW to force
> show tag values with key = "topic"
TO return proper data?

HELP!? ANY ONE? :smile:
THANKS!!!

2

1.Possible bug
Which version of InflxDB are you using? in some old versions, this was a rare bug (without a solution).

2.Wrong/missing serialization
From your telegraf config, I see no mapping for tags, this usually means that everything is mapped as a field, see:

itā€™s pretty easy to see, just have a look at the line protocol you get, either run Telegraf with --test, or look at your output_file since by default it uses lineprotocol

3.duplicate names
Another idea I have is that something bad happened and that name is used both as a tag and a field key (in theory this cannot happenā€¦ but once I ended up in this situation), and the engine is now confused about which one to referenceā€¦ this rarely happens and leaves behind errors in the log so it shouldnā€™t be that hard to spotā€¦ (just run a SHOW FIELD KEYS)ā€¦

3

Version! Thatā€™s was the problem. I was using influxdb 1.6.4-1build1 from Ubuntu 20.04.3 LTS repository.
When I switched to InfluxDB2 everything woks fine :smiley:
THANKS!