Aggregate functions in InfluxQL are not giving output when a "tag" value is passed instead of "field"

Question

I am using influxQL to query data from influxdb in order to see visualisations on Grafana. There are columns in the table , those are basically fields and tags, I want to count the distinct values of a tag column by grouping it by hourly time frame. this is my query

SELECT COUNT(DISTINCT("tag")) FROM "measurement" GROUP BY time(1h)

I am not getting output after running this total unique tags = 10

Time         tag
1:00:00       1
1:10:10       4
1:30:10       3
1:45:00       1
2:00:00       3
2:50:00       3
3:00:00       10
3:13:00       5

What I am expecting -

Time         tag
1st hour      3  ( because 1,4,3 are 3 unique ids in that hour frame)
2nd hour      1
3rd hour      2

Answer 1

COUNT DISTINCT cannot be used directly on tag (InfluxQL is not a SQL!), therefore a subquery is needed, e.g.:

SELECT COUNT(DISTINCT "tag") as "counttag"
FROM (
    SELECT "time","tag","Value(field)"
    FROM "measurement"
    WHERE $timeFilter
)
GROUP BY time(1h)

Make sure you have used UTC for timestamp in the InfluxDB and keep in mind that Grafana "move" results to your local browser timezone by default.