For example I have Gauge my_metric.

my_metric{job="1"} 1.0 - at 13:00 - first
my_metric{job="1"} 1.0 - at 13:10
my_metric{job="1"} 1.0 - at 13:20 - last

How can I get timedelta from first to last metric? I need to get 13:20 – 13:00 = 20 minutes.

I tried to do.
I got timestamps for each metric:

timestamp(my_metric))

Than I tried to get delta:

delta(timestamp(my_metric)))

but have an error:

bad_data: invalid parameter "query": 1:7: parse error: expected type range vector in call to function "delta", got instant vector

If i try to get range vector from timestamp:

delta(timestamp(my_metric))[1h])

I have an error:

bad_data: invalid parameter "query": 1:67: parse error: ranges only allowed for vector selectors