I am perplexed at this point. I spent a day or three in the deep end of Influx and Grafana, to get some graphs plotted that are crucial to my needs. However, with the last one I need to total up two metrics (two increment counts, in column value). Let's call them notifications.one and notifications.two. In the graph I would like them displayed, it would work well as a total of the two, a single graph line, showing (notifications.one + notifications.two) instead of two separate ones.
I tried with the usual SELECT sum(value) from the two, but I don't get any data from it (which does exist!). There is also merge() mentioned in the documentation of Influx, but I cannot get this to work either.
The documentation for merge requires something like:
SELECT mean(value) FROM /notifications.*/ WHERE ...
This also, comes back as a flat zero line.
I hope my question carries some weight, since I have far from enough knowledge to convey the problem as good as possible.
Thank you.
In InfluxDB 0.9 there is no way to merge query results across measurements. Within a measurement all series are merged by default, but no series can be merged across measurements. See https://influxdb.com/docs/v0.9/concepts/08_vs_09.html#joins for more detail.
A better schema for 0.9 is instead of two measurements: notifications.one and notifications.two, have one measurement notifications with foo=one and foo=two as tags on that single measurement. Then the query for the merged values is just SELECT MEAN(value) FROM notifications and the per-series query is then SELECT MEAN(value) FROM notifications GROUP BY foo