Draw static lines

Hi, I’m using grafana on influxdb for water height, everything is ok, but I have static data like a max height for a named date (flood dates) and I want to draw them has horizontal line on same graph. Is there a way to do this? SHould I store this in influxdb first, but it’s not time series, it’s constant data?

Looks related: https://github.com/grafana/grafana/issues/9085

Even if you say that it’s constant, it must still have a start time and end time. One way to do it would be to add a series. My suggestion is to add four points :

0.0, start time
constant, start time
constant, end time
0.0, end time

Then add this series to a graph, remove the mean() and group by time($__interval). Go to the Display tab, Under Stacking& Null value, Null value, change to connected. That will connect the four points together.

You could use a threshold line and deselect the fill, leaving only the threshold line.
Works in my use case at least:

How to give threshold value dynamically?
In my use case, I am plotting an average horizontal line, by giving static value I am able to plot a average line. But how to update the average line when ever data is inserted.