Running Piwik 1.9, I have it scheduled to delete old visitor logs every week.
The settings page says that it last did an automatic deletion at the right time, but nothing has been deleted. My database is still at 3Gb, and clicking the “Purge DB now” button never completes.
What can I do to delete the visitor logs older than 90 or 120 days?
see last 2-3 posts here for more background: 301 Moved Permanently
I found this hint…
If it’s a FCGID specific problem, you might want that all those warnings go away simply by switching your site over to CGI. You can do that by going into Server Configuration -> Website Options, and changing the PHP Execution Mode.
Can you try this?
I also found this that may help…
http://www.heath-whyte.info/david/computers/mod_fcgid-timeouts-and-downloads
Interesting. Switching it to CGI, then clicking on “Purge DB now” seems to have finally worked.
It took nearly 9 hours for the purge to complete, but it finished it!! 
My Piwik database is now a more manageable (and movable) 1.2Gb, and since the data import crunching is over, we can move the site to it’s permanent home.
Thanks!
good news thanks following up!
Awesome glad it helped!