Set up "min Interval" for Grafana / Influxdb dashboard

[ccoenen]

I am using the influxdb dashboard example from the README and generally it's working fine.

One thing I would like to see improved, though, is setting a "minimum interval" for each of the panels. Since the default suggested config for collection is 5 seconds, it would make sense to also set 5s as minimum interval for the dashboard.

When no minimum interval is set, the interval is derived from the available screen space (basically "what timeframe is visible" divided by "how many pixels do I need to fill"). This may lead to intervals lower than 5 seconds, one second in this following screenshot. This also leads to disconnected data points:

This setting can be overridden with the min interval, which is what I am suggesting in this request. If I set this to the matching 5 seconds (or more coarsly would also work) this will then set an automatic lower bound for the interval. This will fix the chart, because now it knows that there are no "missing" values between the individual measurements and the line chart can be drawn continuously.

To reproduce, use OhmGraphite with Influxdb and the suggested dashboard. Collect some data (a few measurements will do, no need to collect hours) and just zoom in far enough. Once there's (basically) more pixels than measurements, this should appear.

[nickbabcock]

Good points! I think this falls under the larger task of #246. Now that prometheus dashboard, which has been championing a new layout for dashboards, has settled down -- I think it is a fine time to start porting over improvements to the influxdb (and other) dashboards. It may be a bit of a cumbersome task, so I haven't dedicated time to syncing all the dashboards yet.