问题
Is it possible to write a InfluxDB query that will give me the number of milliseconds since the last entry in a time series? I'd like to add a single-stat panel in Grafana displaying how old the data is.
回答1:
I don't think it is possible since you are not able to query the time alone. A influxdb query needs at least one non-time field in a query. You could workaround that by double saving the time in a extra field which you are able to query alone.
But you still want to use now() - "the extra time field". But as far as I found out you also can't use now() inside grafana.
Update: there is a [Feature-Request] now on grafanas github. Make sure to vote it up so it gets implemented one day: https://github.com/grafana/grafana/issues/6710
Update 2: The feature got finaly implemented -> See my answer here: How to show "33 minutes ago" on Grafana dashboard with InfluxDB?
来源：https://stackoverflow.com/questions/39534892/influxdb-query-milliseconds-since-last-data-point-in-a-time-series