We allow our users to run reports off our site. We are interested in monitoring the date ranges entered by the user. Obviously that will tie directly to the amount of data returned and page load times. Is it possible to define custom variables to capture start and end dates and tie those to a particular page load resulting from the submitted request? If we do that, is there a way to calculate the size of the interval after the fact or would we need to calculate that at the same time and save it into a 3rd variable. Besides wanting this information for performance reasons, we’d like to make better decisions as to the default values we set for the reports.
Yes it is possible to do what you want.
To tie back and see which pages were used with given date range, you can use Segmentation: Segmentation - Compare segments of visitors - Analytics Platform - Matomo
I recommend to compute size of date interval, at the time, and store it in custom var.
In the future we plan to make Piwik better at measuring Apps, Softwares, and other things like wearables and sensors. So stay tuned as well for more goodness in next months and years!