Panel Graph, influxDB, derivative function and autoscale

Hi,

I am confronted with an autoscale problem with the graph panel and an influxdb datasource and more particularly with a use of a derivative function.
I get the snmp counter64 from a router :
ECNI_STC_RX_L3VPN="snmpget -v 3 -l authPriv -u user -a SHA -A passphrase1 -x AES -X passphrase2 ip_adresse:161 .1.3.6.1.2.1.31.1.1.1.6.176 | sed -E 's/iso.3.6.1.2.1.31.1.1.1.6.176 = Counter64: //'"
and I store this value in my InfluxDB database.

In the graph panel, I applied this function.
SELECT 8 * DERIVATIVE("ECNI_STC_TX_L3VPN", 1s) FROM "ECNI"

Everything works fine but the graph keep in mind the max value of the result and don’t autoscale the Y axis.

I noticed that without the use of a function, the autoscale works fine.
So, the source of my problem is around of this function.

Have you ever been confronted with this type of problem and if so, do you have a track to solve this ?

Thanks for your idea

Mathieu

Ubuntu 16.04.3 LTS
grafana v4.6.3 (commit: 7a06a47)
ii influxdb 0.10.0+dfsg1-1 amd64