When you make a request for statistics, the monitoring service might adjust the specified roll-up interval times to improve the appearance of statistics graphs in a graphical interface.
The monitoring service adjusts the start time of a data collection request when it is not an exact multiple of the interval length. In these instances, the start time is rounded downward to the previous UTC time that is a multiple of the interval. All subsequent intervals of the data collection are also adjusted to align with the new start time.
For example, if the start time is 10:31 and the interval length is 1 hour, the monitoring service adjusts the start time to 10:00 and the roll-up intervals have the following continuous pattern.
- 10:00 to 10:59:59.999
- 11:00 to 11:59:59.999
- 12:00 to 12:59:59.999
The monitoring service does not adjust the end time of a data collection. Consequently, the response to a statistics query might contain one more data value than expected, or an incomplete final interval might be lengthened.
