InfluxDB - How to retrieve differents metrics

Hi all,

I use Nagios with pnp.
I would like to make Dashboards more sexy and more dynamics.
My selection contains Grafana, Elastic Stack and Power BI.
For now, i’m trying Grafana.
I have installed Nagflux and now i have an InfluxDB database.

For simple metrics, all works fine.
But i monitor Memory Usage on my hosts. This check returns different values like memory available, total, used …


In pnp4nagios, graphs are like this:

So, all is correct.

But in Grafana, when i make a query, i only have one metrics.
My query:

SELECT first(“value”) FROM “metrics” WHERE (“host” = ‘datacenter-1’ AND “service” = ‘Memory Usage’) AND time >= now() - 6h and time <= now() GROUP BY time(15s) fill(null)

It return only Total memory metrics.

A SELECT mean(“value”) give values which not match anything

SELECT mean(“value”) FROM “metrics” WHERE (“host” = ‘datacenter-1’ AND “service” = ‘Memory Usage’) AND time >= now() - 6h and time <= now() GROUP BY time(15s) fill(null)

Could anyone help me ?
Thanks