Metric sum per day

Hello everyone,

I am totally new to Grafana and the world of programming in general. I am an Environmental Engineering student out of Germany and working in the laboratory of the University. I have a machine here I am kind of responsible for. In the last time i had the idea to improve the machine a bit in terms of data usage. So I setup a postgres instance on a local server here and configured an logical replication to have a fallback in case of dataloss. Now I want to use this fallback server to be monitored by grafana. Here not only the performance of the server but more importantly for me the values the machine is creating.
overview%20tabel

I am facing at the moment the following problem:

I have a column “Value5” which in which i can find the total gasproduction of one reactor. Every five minutes the machine is saving this value and it’s a sum. I added a picture of that so you can better understand what I mean.

For me its interesting to see how much gas was produced in one day ore in one week. So I created the following query with the build in query builder of grafana.

As you can see here I am looking for the max per day and then the delta. So I will get how much Litre was produced in one day.

My Problem now is that sometimes the machine has a problem and reboots. When this happens the Gascounter “Value5” will get a reset. So it will start again with 0. With the query at the moment I will get a big negative value displayed. Do you know a solution for that problem? What can I write into the query that he will know and don’t give out a negative value?

I use Grafana v 6.0.2 and Postgres 10

Best regards

Harm Wilken