Graph from independent data points

No success in “putting values to database”.
I’m using influxdb + grafana. But I can’t find any forum posts that describe my case.
I have also tried to use REST API, but got stuck: https://community.openhab.org/t/rest-api-persistence-service-not-modifiable-influxdb/70710.
I can’t use simple item value update rule, because it would only persist data at given moment (now).
As my data is with future timestamps- I need to write data to database as value-time pairs.