Long-term operations in Grafan

Question

How to subtract twice in Grafana ? Or add two together, split into each other, etc ?? I found vague clues on the Internet on how to accept the differences between timeouts, but nothing that really tells me how to do this. I use Grafana v2.0.2 with Influxdb v0.8 and have played a lot with graph controls to discover things like the difference operator, which I can apply, but I have no idea how to use it. I tried to find documentation on this, but the closest I can find is largely silent on this topic, and also looks a bit dated, as the interface has changed since these screenshots were taken.

Thanks!

Answer 1

This feature was added as question 177 from Grafana :

Set up two series, click the eye icon to hide them, and place the third with the previous separation.

This only works in Graphite (I would also like to work on inflow)

Answer 2

InfluxDB v0.12 supports the following operations:

Arithmetic operation on the result of the aggregation function:

 SELECT 10* MEAN(usage_system) AS avg FROM cpu WHERE time > now() - 10s; 

or arithmetic operation between fields:

 SELECT usage_system + usage_user AS avg FROM cpu WHERE time > now() - 10s; 

and, most importantly, you can perform an arithmetic operation between the results of the aggregation function:

 SELECT MEAN(usage_system) + MEAN(usage_user) AS avg FROM cpu WHERE time > now() - 10s GROUP BY host; 

not supported by the Grafana graphics editor (but you can record it manually).

Answer 3

Another possible solution (which I used only with graphite) is to use the sumSeries and scale functions. To add two time series, do

 sumSeries(first.time.series, second.time.series) 

and get the difference do

 sumSeries(first.time.series, scale(second.time.series, -1)) 

This must be done using a text editor for indicators.