Thank you for the tip, I partially solved my problem.
I was assuming you could have quoted strings as tag values, since in their “Time to Awesome” document they have this kind of examples:
measurement1,tag1="tagvalue1",tag2="tagvalue4" field1=1i 1626118620000000000
I recall trying to put a literal value, such as tag1 without succeeding anyway, but this was probably due to the second error source, an issue with timestamp.
If I use the correct syntax you suggested specifying a seconds precision:
certificates,category=Blended\ Learning courseid=2403i,completion=100 1656367200
I still get an error. If I drop the timestamp the line protocol works:
certificates,category=Blended\ Learning courseid=2403i,completion=100
According to ChatGPT, the new “Oracle” (in the ancient greek meaning of the term ):
In InfluxDB line protocol, the timestamp should be a 64-bit signed integer, which represents the number of nanoseconds since January 1, 1970 UTC. This means that the timestamp can have up to 19 digits, including negative values for timestamps before the epoch.
My Unix timestamp comes straight from a MariaDB table and is 10 digits wide, corresponding to elapsed seconds since origin of Unix time.
Since the default precision is nanoseconds, I added 9 digits to convert it to the right UOM:
certificates,category=Blended\ Learning courseid=2403i,completion=100 1656367200000000000
but InfluxDb still raises an error.