Selecting Year as the timeframe of my most visited site, i now know why the database had an incredible increase in size since i installed a new Piwik with a new DB a few months ago.
All URLs are in double in the database.
In the widget “exit link”, i have both urls that begin by http:// and that dont.
Like this :
* http://fr.wikipedia.org * fr.wikipedia.org
Maybe a php script could be run to modify old urls to the new format. And this also need to be done for the file download info.