It seems Grafana reduces data points when the time range is zoomed out. I wonder what aggregate function(avg, max, etc…) is applied for data points.
The aggregation will be defined in the query editor. Maybe look at that and see if it clears things up?
My dashboard doesn’t apply aggregation in query.
My scrape interval is 5 second. But When I set the time range to the recent 7 days and move a mouse pointer in the graph, It seems the timepoint’s interval is reduced to 15s.
Dare I ask what your screen resolution is? At 5-second spacing, a 7-day interval would contain 120,960 data points. So unless you’re using a screen with that many pixels across the horizontal direction, it’s not really clear to me how individual data points would even be visible.
In fact I’m surprised that you would even get 15-second resolution, since that would require ~40K pixels. Are you sure it’s not 15 minutes?
Anyway, to answer your question - if you don’t have an aggregation in your query, then I think Grafana will simply try to plot all your data points. That will probably look messy, since you would end up with multiple datapoints superimposed on each individual pixel. As for the tooltip when you hover over the chart, that will simply show the value of one of the many points that are plotted on the pixel you’re hovering over.
Thank you for answer. I misunderstood that grafana downsampled data.
And it was 15-minute resolution.