Need a query function which returns an actual increase in counter values within a time interval and handles counter reset cases

[anantha96]

Is there a functionality using which we can get the difference in the values of counter samples within the time interval, while handling counter reset case and excluding the extrapolate functionality?

We tried using the increase() function, but it returns an extrapolated result. We have observed that the difference between the actual increase and the extrapolated result is considerably high.

Example:
If we are calculating the increase in a metric "node_disk_read_bytes_total" every 5 mins, with prometheus scrape interval set as 1 min:

• Consider the following sample values for the metric "node_disk_read_bytes_total" within a 5 mins interval :
  [23758450955264 (F), 23758499419136, 23758518625280, 23758519292928, 23758519870464 (L)]

Result of the increase function:

• Extrapolated value returned by increase function over 5 mins: 86144000

Our requirement is a function which:

• Handles the counters resets similar to increase function
• And returns the actual difference b/w the values of the first sample(F) and Last sample(L) within the specified interval : 68915200