We need to get the sum of statistics data from the "beginning" which means from the moment we added site to the system (ts_created field in site table).
It can be very useful for example in video plugin when we can get the sum of all video events (i.e. video_play) from the first time video appeared online. It is quite important feature.
To do what you want to do, the best thing I can think of is to build a filter that would sum up the DataTable_Array of every year and output only the sum.this could look like:
This filter could use the DataTable::addDataTable The only thing to think of is that the DataTable_array could be simple:
date=A data A date=B data B
looping over the set and sum the datatable should work.
For the version where the rows are themselves made of dataTable_Array
idsite=1 date=A data A date=B data B idsite=2 date=A data C date=B data D etc.
we want the output
idsite=1 data A+B idsite=2 data B+D
Important note: when summing web analytics data, we have to make sure we don't sum some fields like "nb_uniq_visitors", as it is not correct to sum uniques
I believe this should be done on the client side. marking as won't fix for now.
Actually this feature is really Custom Date Range since all it does is summing the data and caching it like a normal report, see #572