Thank you for raising your query. I will try to give you an idea about each of these metrics.
In general , we poll at 5 minute frequency for RDS (you can choose your frequency if required) . But , from AWS , we expect 3-5 data points for these 5 minutes by default. So , we try to give you the possible meaningful information out of these.
With respect to database connections, there are 4 ways to configure threshold.
Summation of connections for last 5mins. It gives the total number of connections.
Average connections in use for last 5mins. If there are 3 points to compute this , we divide the overall summation by 3 and provide you an average.
Maximum number connections used in 5mins. Say ,there are 3 points available for the 5 minutes on AWS, the gives the maximum value out of those .
Exact number of active/open connections at polling time. Say, there are 3 points for these 5 minutes from AWS , we pick the 3rd point as the value for this. This gives the value of the database connections at the time when the data is polled for.
Hope this helps. Kindly let us know if you require more details.
Ananthkumar K S